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I I 






Translated Jrcm the Third Edition^ with an Introduction and 

Notes^ by 











r ^' - ' ' ' ' '" ' * 


« f 

-r I , 

/ •■ 





Translator's Preface . . . . xxi 

^ Papers by the Author published in the 

"Revue Scientifique" .... xxv 

Introduction ...... i 



The Theory of Intra-atomic Energy and the 
Passing-away of Matter. 

§ I. The new ideas on the Dissociation of Matter — Matter not 
V> indestructible — Radio-activity universal property of Matter 

^ — Intra-atomic Energy — General Propositions. § 2. Matter 

-^ and Force — Matter a variety of Energy — All Phenomena 

transformations of Equilibrium — Energy consequence of 
^ Condensation of Nebula. § 3. Consequences of the 

^ Vanishing of Matter — Nothing created, everything perishes 

<v — Destruction of Matter very slow — Indestructibility of 

Mass must go — Possibly Conservation of Energy also — 
Atoms Planetary Systems . . . . .5-18 


History of the Discovery of the Dissocia- 
tion OF Matter, and of Intra-atomic 

Author's discovery of Black Light — Of radio-activity of all 
bodies — M. Becquerel on the reflection, etc., of Uranium 
Rays — Acceptance of author's theory by M. de Heen — 
Unpopularity at outset — Testimony of Mi Dastre — Of M. 
Lucien Poincar^ — Of English writers — M. de Heen's 
comparison of the discovery of Black Light with that of 
X Rays — M. Georges Bohn's appreciation . . 19-34 






Intra-atomic Energy: Its Magnitude. 


§ I. The Existence of Intra-atomic Energy — Emission of 
particles with enormous speed by Matter when Dissociating 
— Energy developed equal to that of 1,340,000 barrels of 
gunpowder — This Energy within not without the Atom — 
Its Origin. § 2. Estimate of Quantity of Energy in Matter 
— That contained in the smallest coin sufficient to send 
train more than four times round the Earth — Other measure- 
ments by Rutherford, Max Abraham, and J. J. Thomson. 
§ 3. Forms of Energy condensed in Matter — Kinetic Energy 
in pin's head = 208, 873,000, 000 kilogramm^tres. § 4. Utili- 
zation of Intra-atomic Energy — Useless at present because 
Dissociation of Matter cannot be hastened — This Difficulty 
overcome, power will be free to all . . . . 35-51 

Transformation of Matter into Energy. 

Old Idea that Matter had nothing in common with Energy — 
Difficulty of upsetting this notion — Lord Kelvin's first view 
— New Ideas only make their way gradually — Influence of 
Prestige on scientific belief ..... 52-59 


Forces derived from Intra-atomic Energy — 
Molecular Forces, Electricity, Solar 
Heat, etc. 

§ I. Origin of Molecular Forces — Cohesion, chemical affinity, 
etc., only explicable as Intra-atomic Energy. § 2. Origin 
of Electricity — Constantly-increasing importance of Elec- 
tricity — Electricity form of Intra-atomic Energy set free by 
Dissociation of Matter. § 3. Origin of Solar Heat — Stars 
not necessarily cooling — Heat lost by Radiation may be 
compensated ior by Energy liberated in Dissociation . 60-67 




Objections to the Doctrine of Intra-atomic 

M. Poincare's, M. Painleve's, and M. Naquet*s objection that 
no endothermic combination stable — Answer : Matter 
not stable since easily dissociated — M. A. Gautier's con- 
firmation of this — M. Despaux's objection : quantity of 
matter and energy in the world invariable — Answer : 
facts about radiunx disprove this — M. Duclaud and M. 
Laisant's criticisms — Professors Filippo Re's, Somer- 
hausen^s, and Pio*s opinions — Consequences of sudden 
dissociation of gramme of radium — Annee Scientifique^ s 
and M. Sagaret's remarks . . . . 68 79 




Classic Separation between Ponderable and 
Imponderable — Is there an Intermediate 
World ? 

Lavoisier's Definition and Berlhelot's Approval — Larmor's 
reconciliation of Eiher and Matter — Particles emitted 
during Dissociation of Matter the link with Ether . 80-86 

Immaterial Basis of Universe: The Ether. 

Importance of Ether in Physics — Difficulty of defining its 
Properties — Not a gas — Other opinions — Imponderable 
but condensable — Larmor's opinion that Material Mole- 
cule only Ether . . . . . .87-93 

Different Equilibria in the Ether. 

All ethereal equilibria very unstable — Vortex ring theory — 
Explains Gravitation — M, A. Gautier's opinions on this — 
M. Benard's experiments — Matter a particular state of 
ethereal Equilibrium ..... 94-100 





Interpretation of Dissociation Experiments. 


§ I. The First Interpretations — Crookes' "ultra-gaseous" 
state — Kinetic Theory of gases described — Cathode Rays 
really identical with . Particles of dissociating Matter. 
§2. Interpretations now current — Discovery of X and 
Uranium Rays make old explanations untenahle— ^ 
Ionization merely Dissociation — Contrasts between 
Ordinary and Ionic Electricity — Dissociation Products 
identical for all substances .... IOI-II2 

Products of Dematerialization of Matter. 

§ I. Classification of above Products— rCIassification necessary 
— Can be divided into six Classes. § 2. Characteristics 
of Dissociation Elements: viz., Emanation, Positive and 
Negative Ions, Electrons, Cathode Rays and X Rays . 11 3- 1 29 


Dematerialization of specially Radio-active 

§ I. Products of Dematerialization of such Substances. § 2. 
a rays or Positive Ions. § 3. /3 rays or Negative 
Electrons. § 4. 7 or X rays. § 5. Semi-material Emana- 
tion of Radio-active Substances. § 6. Induced Radio- 
Activity. All these stages in return of Matter towards 
Ether ....... 130-147 

Dematerialization of Ordinary Bodies. 

§ I. Causes of Dematerialization — How Dissociation proved. 
§ 2. Dissociation by Light. § 3. By Chemical Reactions. 
§ 4. By Electric Action. § 5. By Combustion. § 6. By 
Heat. § 7. Spontaneous Dissociation. § 8. Part played 
by Dissociation in Natural Phenomena . . . 148-162 




Artificial Equiubria of Elements produced 
BY Dissociation. 

Possibility of photographing momentary Equilibria — ^Attrac* 
tions and Repulsions of dissociated Particles — Globular 
Electricity — ^The Ionic Fluid and its Geometrical Forms 163*171 

How Matter c\n Dissociate. 

§ I. Causes of modi£cation of molecular and atomic struc* 
tures — Equilibria disturbed^ by slight but appropriate 
action — Acoustic analogy. § 2. Mechanism of Dissoci' 
ation. § 3. Causes of Dissociation of very Radio-active 
Substances. §4. Does Radium Exist ? . . .172-187 




Properties of Substances intermediate be- 
tween Matter and Ether. 

Only irreducible characteristic of Matter Mass — Variation of 
Mass in case of Electric Fluid — Kaufmannand Abraham's 
Researches on this — Particles real link between Ponder- 
able and Imponderable ..... i88*i97» 

Electricity a ^emi-Material Substance. 

§ I. Radio-active and Electrical Phenomena. § 2. Elements 
emitted by Electric Machine compared with Emissions 
of Radio-active Bodies — Aigrettes identical with a, /3, and 
7 Rays — Aigrettes also give ultra-violet light — Experi- 
ments with Dr. Oudin ..... 198*214 




Properties of Electric and Material Fluids 

Superior Mobility of Electric Fluid — Curnu's Analogies — 
Neutral Electric Fluid not observable — Susceptibility to 
Gravitation real Distinction .... 215-219 

Movements of Electric Particles. 

Example of Electrified Sphere at Rest : no Magnetic Force — 
In Motion, Magnetic Force appears — Acceleration of 
Motion produces vibrations of Ether — Rowland's and 
Zeeman's Experimen,ts — Electronic Theory . . 220-227 




Constitution of Matter and Forces which 
MAINTAIN Material Edifices. 

§ I. Former Ideas on Structure of Atoms. § 2. Current 
Ideas on Constitution of Matter. § 3. Magnitude of 
Elements of Matter. § 4. Forces which maintain Mole- 
cular Structures. § 5. Attractions, Repulsions and 
Equilibria of Isolated Molecules — Osmotic Phenomena 
and Leduc's Experiments .... 228-247 


Variations of Material Equilibria with 
Change of Environment. 

§ I. Mobility and Sensibility of Matter. § 2. Variation of 
Equilibria with Change of Medium — Matter in incessant 
Motion ....... 248-255 




Various Aspects of Matter. 

§ I. Gaseous, Liquid, and Solid States. § 2. Crystalline 
State of Matter and Life of Crystals— Von Schron's 
Experiments — Double Generation of Crystals . . 256-262 

Unity of Composition of Simple Bodies. 

§ I. Are all Simple Bodies formed from One Element? 
§ 2. Are Simple Bodies of Unvarying Fixity? — Berthe- 
lot*s Experiments — Chemical species variable . . 263-273 

Variability of Chemical Species. 

§ I. Variability of Simple Bodies — Author's Experiments on 
Variation of Elements by Actions by Presence — Trans- 
mutation of Elements. § 2. Variability of Compounds — 
Action of Caffeine and Theobromine combined — Modifi- 
cation of Atomic Equilibria possible . . . 274-287 

Chemical Equilibria of Material Substances. 

§ I. Chemical Equilibria of Minerals. § 2. Of Organic Sub- 
stances — Living Being an Aggregate of Cells . . 288-295 


Intra-atomic Chemistry and the Unknown 
Equilibria of Matter. 

§ I, Intra-atomic Chemistry. § 2. Colloid Metals. § 3. 
Diastases, Enzymes, Toxins, and Action by Presence — 
Catalyzers Liberators of Energy. § 4. Oscillatinp; 
Chemical Equilibria ..... 296-306 


Birth, Evolution, and End of Matter. 


§ I. Genesis and Evolution of Atoms — Nebulae and the 
Spectroscope— Atom follows law of Birth, Growth, and 
Death. § 2. End of Matter — Electricity one of its last 
stages. Ethereal vibrations last of all. § 3. Conclusions, 
Recapitulation, and Functions of Hypothesis . . 307-319 


Prefatory Note . . . . 321 


General Methods of verifying Dissocia- 
tion ..... 322-329 


Method of verifying Dissociation by Light 330-337 I 



Dissociation by various Parts of Spectrum 338-356 


Possibility of rendering Ordinary Bodies 

Radio-active .... 357-359 



Negative Leak caused by Light . 360-376 

Dissociation by Combustion . . 377-382 

Dissociation by Chemical Reactions . 383-389 

Dissociation of very Radio-active Bodies . 390-393 

Ionization of Gases .... 394*398 


Emanation from All Substances . . 399-402 


Absence of Radio-activity in finely-divided 

Bodies ..... 403 

Variability of Chemical Species . 404-414 




Passage through Matter of Dissociated 

Particles ..... 415-418 


Historical Documents . . 419-428 

Index of Authors .... 429 

Index of Subjects- .... 432 



Artificial' equilibria imposed on -elements proceeding 

from the dematerialization of Matter . . Frontispiece 

I and 2. Apparatus employed in 1897 by Gustave Le Bon to 
' demonstrate, by the absence of polarization, that the 
- radiations emitted by salts of ur&nlum are not invisible 
light . . . , . , . . •23 

3. The three orders of radiations emitted by a radio-active body 

and separated by a magnetic field . . . 131 

4. Iladiation of particles of dissociated matter not subjected to 

attractions or repulsions ..... 163 

5. Attraction of particles of dissociated matter charged with 

positive and negative electricity .... 163 

6. Repulsion of particles of dissociated matter emitted by two 

points and moving in the direction of the lines of force . 164 

7. Repulsion of particles of dissociated matter emitted by several 

pomts ••..... 164 
8, 9, 10, II. Several figures obtained by compelling particles of 
dissociated matter to move and repel each other in certain 
directions • . . • . . . , 165 

12, 13, I4f 15. Apparent materializations produced in space by 

utilizing the repulsions of dissociated matter . . 167 

16 to' 19. Photographs of geometrical figuires obtained by con- 
fining the ionic fluid to plates of resin . . .170 

20. Curve showing one of the fundamental properties of the 

substance intermediate between ponderable matter and 

the imponderable ether . , . . . .191 

21. Radiation of the electric pa-rticles from a single pole . . 202 




22. Photograph of the aigrettes produced by the particles emitted 

by one of the poles of a static machine . . . 203 

23. Positive and negative electric particles, which are formed at 

the two poles and attract each other . . . 203 

24. Concentration of the electric particles into a few lines from 

which results a dischai^e in the shape of sparks . . 203 

25. The visible passage through a material obstacle formed of a 

plate of glass or ebonite . . . . . 207 

26. Photograph of the efHuves proceeding from the dematerializa- 

tion of matter during their passage through a material 
obstacle such as a plate of glass or ebonite • . 208 

27. Impressions produced by ions from an electrified point 

through a sheet of black paper . . . .210 

28 and 29. Repulsions and attractions of molecules in liquid . 243 

30 and 31. Photographs of artificial cells resulting from molecular 

attractions and repulsions in liquid . . . 244 

32. Photograph of artificial cells obtained by diffusion ', . 245 

33* 34* ^^^ 35* '^^^ three phases of the successive formation of 

a crystal ....... 258 

36. Classic method used to measure the radio-activity of bodies . 323 

37. Apparatus for reducing the rapidity of the loss of electricity 

produced by radio-active bodies • • . . 325 

38. Condensing differential electroscope of the author . . 327 

39. Apparatus used to demonstrate the dissociation of matter by 

the action of solar light . . . '331 

40* Apparatus used to show the dissociation of matter under the 
influence of the ultra-violet light produced by electric 
sparks ....... 333 

41 and 42. Determination, by means of photography, of the 
transparency of bodies for the various regions of the 
spectrum ....... 335 

43. Photographs showing the disappearance of the solar ultra- 
violet on certain days caused by unknown influences . 343 



44. Mechanism of the discharge of an electroscope by the effluves 

of the dissociated matter disengaged from the metals 
struck by solar light ..... 348 

45. Comparison of the dissociation of spontaneously radio-active 

bodies and of metals under the influence of light . . 358 

46. Apparatus employed for the study of the leak of electrified 

bodies under ultra-violet light .... 362 

47. Apparatus for showing the leak of electricity under the influ- 

ence of flames according to the distance and the nature 
of the bodies on which the action is produced. The 
charged strip on the electroscope draws to itself the ions 
which discharge it ..... 378 

48. Apparatus showing visibly the electric leak under the action 

of the particles of dissociated matter contained in the 
gases of the flames ..... 379 

49. Apparatus showing the action of dissociated matter contained 

in the gases of flames on an electrified body contained in 

a metal cage ...... 381 

50. Study of the dissociation of matter by chemical reactions . 384 

51. Apparatus of Gustave Le Bon and Martin, used for deter- 

mining the part played by water vapour in the phosphor- 
escence of phosphorus ..... 387 

52. Experiment on the properties of gases dissociated by flames . 395 

53. Recombination of the ions obtained in the dissociation of 

matter by chemical reactions .... 397 

54. Arrangement by which the transformation of the properties 

of mercury are got through combination, under the 
influence of slight pressure, with traces of magnesium . 406 

55. Decomposition of water by mercury containing a trace of 

magnesium ...... 406 

56. Decomposition of water by magnesium containing traces of 

mercury ....... 407 

57 to 60. Formation of tufts of alumina on strips of aluminium 

covered with invisible traces of mercury . . . 409 




6i. Arrangement of the experiment which allows us to give to 
a strip of aluminium, after its extremity has touched 
mercury, the property of decomposing water, and of 
transforming itself entirely into alumina, even when the 
mercury is withdrawn after the decomposition of the 
water has commenced ..... 410 

62. Sketch of the arrangement for giving to the efHuves produced 
by particles of dissociated matter sufficient tension tu 
enable them to pass through thin plates of nonconducting 
bodies, such as glass and ebonite .... 416 


There is, fortunately, no need for me to introduce 
Dr. Gustave Le Bon to the British public, inas- 
much as his works on psychology have a European 
reputation, and his Psychology of Crowds (long since 
translated into English) has become, in some sort, a 
classic. About ten years ago, however, he began to 
turn his attention to physical science, with the result 
that he entered upon the long course of experimental 
research which is summarized in the following pages. 
This led him to the conclusion — to put the affair in 
its simplest form — that all matter is radio-active in 
the same manner as uranium, radium, and the other 
so-called radio-active metals, and that this radio- 
activity is but a step in the process by which it 
gradually sinks back into the ether from which it 
was originally formed. To this he has lately added 
the corollary that, in the course of this disintegration, 
energies of an intensity transcending anything of the 
kind previously observed are very slowly and gradually 

Conclusions so subversive of all that formerly 
passed under the name of scientific teaching could 
hardly be promulgated without causing an uproar, 
and that which followed the first ventilation of them 


xxii translator's preface. 

left nothing to be desired on the score of vehemence. 
In France, even more than in England, it has always 
been considered an impertinence for any one not 
engaged in the tuition of youth to possess original 
ideas on any scientific subject, and the violence of 
Dr. Le Bon's adversaries was only equalled by the 
volubility with which they contradicted themselves 
and each other. How this storm gradually abated, 
and was succeeded first by impartial consideration 
and then by a pretty general acceptance of his 
theories, he tells us at sufficient length in the 
book itself. But I may perhaps remark here that 
his earliest adherents on the Continent were drawn 
from the ranks of those who — as was my own 
case until some two years ago — had no other ac- 
quaintance with him than through his writings. 

In our own country the same thing occurred on a 
smaller scale and with a difference. No sooner had 
the volume of which this is a translation reached 
England than it was assailed, with more rashness 
than ingenuousness, by two of the younger members 
of the University of Cambridge. As I have dealt 
elsewhere^ with the one of them who constituted 
himself the spokesman of the two, there is no occa- 
sion for me to re-open the polemic; but it may 
be noted that this time Dr. Le Bon's assailants 
admitted that his* theory was (to use their own 
words) " in the main correct," and contented them- 

^ See the Aihettautn of February l^\h and 24th, and of March 3rd, 
lOth, 17th, and 24th, 1906. 

translator's preface. xxiii 

selves with challenging the sufficiency of hi^ experi- 
ments and the originality of his doctrine. To those 
who have studied without prejudice the controversies 
which have raged round nearly eyery scientific general- 
ization on its first appearance, this will doubtless 
appear but a premonitory symptom of its universal 
acceptance in the near future. They will be con- 
firmed in this view by the fact that over 12,000 
copies of this book have been sold in France since 
its publication in June 1905, which, in the present 
state of the book market, may be considered an 
extraordinary event. 

The rendering of the work into English has been 
in a double sense a labour of love, my task having 
been much facilitated bv Dr. Le Bon's bold and 
positive style, as well as by his clear and excellent 
French. But, while an author necessarily and justly 
looks upon his translator as a traducer, it is seldom, 
perhaps, that a translator imbued with the critical 
spirit for long remains satisfied with the literary 
workmanship of his author. I do not venture to 
say, therefore, that there is nothing in these pages 
that would have been better left unsaid, or even 
nothing that could have been more clearly stated. 
What I would recommend to the reader, and 
especially to the expert reader who feels himself 
attracted by them, is to go from their study to the 
original memoirs on which they are based, and of 
which a list is appended. He will there find among 
the deviations and slips which usually attend our 

xxiv translator's preface. 

first faltering steps on the path to scientific truth 
many shrewd and pregnant hints that of necessity 
have made their escape in the process of compression 
into the present volume. 

To Dr. Le Bon's original text I have added a few 
notes, designed for the most part to collate his 
conclusions with the latest researches on their sub- 
ject, and these notes can be distinguished from the 
author's by my initials. 


Royal Institution of Great Britain, 
December 1906. 


Title of Papkr. 


Nature et propri6t6s de la lumi^re noire 

Repouse k quelques critiques . 

Condensation de la lumi^re noire 

Nature des diverses esp^ces de radia- 
tions produites par les corps sous 
rinfluence de la lumi^re 

Propri6t6s desiradiations emises par les 
corps sous rinfluence de la lumi^re 

La Lumi^re noire et les propri6tes de 
certaines radiations du spectre 

La Luminescence invisible 

Transparence des corps opaques pour 
les radiations lumineuses de grande 
longueur d'onde 

La Rayonnement ^lectrique et la trans- 
parence des corps pour les ondes 
hertziennes . 

La Transparence de la niati^re et la 
Lumi^re noire 

L'uranium, le radium et les Amissions 
m^talliques .... 

Les formes diverses de la phosphor 
escence . . ... 

La Variability des esp^ces chimiques 


or "Revue Scientifique.' 

22 F6vrier 1896. 
7 Mars 1896. 
16 Mai 1896. 

20 Mars 1897. 

I Mai 1897. 

29 Mai 1897. 
28 Janvier 1899. 

II F^vrier 1899. 

29 Avril 1899. 

14 Avril 1900. 

1) Mai 1900. 
8 and 1 5 
Septembre 1900. 
22 Decern bre 1900. 



Title of Paper. No. 

La Dissociation de la Mati^re . 
L'^nergie intra-atomique 

La Materialisation de I'Energie 
La Demat^rialisation de la Mati^re 

Le Monde interm^diaire entre la Mati^re 
et TEther .... 

La Dissociation universelle de la 
Mati^re .... 

OF "Revob Scientifique.' 

8, 15, and 22 
Novembre 1902. 
17, 24, and 31 
15 Octobre 1904. 

12 and 19 
Novembre 1904. 

10 and 17 
Decembre 1904. 

9 Juin 1906. 



This work is devoted to the study of the Evolution 
of Matter — that is to say, of the fundamental com- 
'ponent of things, of the substratum of the worlds 
and of the beings which exist on their surface. 

It represents the synthesis of the experimental 
researches which I have during the last eight years 
published in numerous memoirs. In their result 
they have shown the insufficiency of certain funda- 
mental scientific principles on which rests the edifice 
of our physical and chemical knowledge. 

According to a doctrine which seemed settled for 
ever, and the building up of which has required a 
century of persistent labour, while all things in the 
universe are condemned to perish, two elements 
alone, Matter and Force, escape this fatal law. 
They undergo transformations without ceasing, but 
remain indestructible and consequently immortal. 

The facts brought to light by my researches, as well 
as by those to which they have led, show that, con- 
trary to this belief, matter is not eternal, and can vanish 
without return. They likewise prove that the atom is 
the reservoir of a force hitherto unrecognized, although 
it exceeds by its immensity those forces with which we 
are acquainted, arid that it may perhaps be the origin 
of most others, notably of electricity and solar heat. 



Lastly, they reveal that, between the world of the pon- 
widely separate, there exists an intermediate world. 

For several years I was alone in upholding these 
ideas. Finally, however, their validity has been 
admitted, after numbers of physicists have deter- 
mined in various ways the facts I have pointed out, 
principally those which demonstrate the universality of 
the dissociation of matter. It was above all the 
discovery of radium, long after my first researches, 
that fixed attention on these questions. 

Let not the reader be alarmed at the boldness 
of some of the views which will be set forth 
herein. They are throughout supported by ex- 
perimental facts. It is with these for guides 
that I have endeavoured to penetrate unknown 
regions, where I had to find my way in thick 
darkness. This darkness does not clear away in a 
day, and for that, reason he who tries to mark 
out a new road at the cost of strenuous efforts is 
rarely called to look at the horizon to which it may 

It is not without prolonged labour and heavy 
expense that the facts detailed in this volume have 
been established.^ If I have not yet obtained the 
suffrages of all the learned, and if I have incensed 

^ To make this book easier to read, the experiments in detail have 
l>een brought together at the end of the volume, to which they form a 
second part. All the plates illustrating the experiments have been 
drawn or photographed by my devoted assistant, M. F. Michaux. I 
here express my thanks to him for his daily assistance at my laboratory 
during the many years over which my researches have extended. I also 
owe hearty thanks to my friend E. Senechal, and the ..eminent 
Professor Dwelshauvers-Dery, Corresponding Member of the Institut, 
who have kindly revised the proofs of this volume. 


many among them by pointing out the fragility of 
dogmas which once possessed the authority of re- 
vealed truths, at least I have met with some valiant 
champions amongst eminent physicists, and my re- 
searches have been the cause of many others. One 
can hardly expect more, especially when attacking prin- 
ciples some of which were considered unshakeable. 
The great Lamarck uttered no ephemeral truth when 
he said, "Whatever the difficulties in discovering 
new truths, there are still greater ones in getting 
them recognized." 

I should be armed with but scant philosophy 
if I remained surprised at the attacks of several 
physicists, or at the exasperation of a certain number 
of worthy people, and especially at the silence of the 
greater number of the scholars who have utilized my 

Gods and dogmas do not perish in a day. To 
try to prove that the atoms of all bodies, which were 
deemed eternal, are not so, gave a shock to all 
received opinions. To endeavour to show that 
matter, hitherto considered inert, is the reservoir 
of a colossal energy, the probable source of most of 
the forces of the universe, was bound to shock more 
ideas still. Demonstrations of this kind touching 
the very roots of our knowledge, and shaking 
scientific edifices centuries old, are generally received 
in anger or in silence till the day when, having been 
made over again in detail by the numerous seekers 
whose attention has been aroused, they become so 
widespread and so commonplace that it is almost 
impossible to point out their first discoverer. 

It matters little, in reality, that he who has sown 
should not reap. It is enough that the harvest 


grows. Of all occupations which may take up the 
too brief hours of life, none perhaps is so worthy 
as the search for unknown truths, the opening out 
of new paths in that immense unknown which sur- 
rounds us. 




§ I. The New Ideas on the Dissociation of Matter. 

The dogma of the indestructibility of matter is one 
of the very few which modern has received from 
ancient science without alteration. From the great 
Roman poet, Lucretius, who made it the fundamental 
element of his philosophical system, down to the 
immortal Lavoisier, who established it on bases 
considered eternal, this sacred dogma was never 
touched, and no one ever sought to question it. 

We shall see in the present work how it has been 
attacked. Its fall was prepared by a series of earlier 
discoveries apparently unconnected with it : cathode 
rays, X rays, emissions from radio-active bodies, etc., 
all have furnished the weapons destined to shake it. 
It received a still graver blow as soon as I had proved 
that phenomena at first considered peculiar to certain 
exceptional substances, such as uranium, were to be 
observed in all the substances in nature. 

Facts proving that matter is capable of a 
dissociation fitted to lead it into forms in which 
it loses all its material qualities are now very 



numerous. Among the most important I must note 
the emission by all bodies of particles endowed with 
immense speed, capable of making the air a con- 
ductor of electricity, of passing through obstacles, 
and of being thrown out of their course by a magnetic 
field. None of the forces at present known being 
able to produce such effects, particularly the emission 
of particles with a speed almost equalling that of 
light, it was evident that we here found ourselves 
in presence of absolutely unknown facts. Several 
theories were put forth in explanation of them. One 
only — that of the dissociation of atoms, which I 
advanced at the commencement of these researches 
— has resisted all criticism, and on this account is 
now almost universally adopted. 

It is now several years since I proved by experi- 
ment for the first time that the phenomena observed 
in substances termed radio-active — such as uranium, 
the only substance of that kind then known — could 
be observed in all substances in Nature, and could 
only be explained by the dissociation of their atoms. 

The aptitude of matter to disaggregate by emitting 
effluves^ of particles analogous to those of the cathode 
rays, having a speed of the same order as light, and 
capable of passing through material substances, is 
universal. The action of light on any substance, a 
lighted lamp, chemical reactions of very different 
kinds, an electric discharge, etc., cause these efifluves 
to appear. Substances termed radio-active, such as 
uranium or radium, simply present in a high degree a 
phenomenon which all matter possesses to some extent. 

When I formulated for the first time this general- 

^ No exact equivalent for this word can be found in English, and I 
have therefore retained it throughout. — F. L. 


i^ation, though it was supported by very precise 
experiments, it attracted hardly any attention. In 
the whole world one physicist, the learned Professor 
de Heen, alone grasped its import and adopted 
it after having verified its perfect correctness. But 
the experiments being too convincing to permit of 
long challenge, the doctrine of the universal dissocia- 
tion of matter has at last triumphed. The atmo- 
sphere is now cleared, and few physicists deny that 
this dissociation of matter — this radio-activity as it is 
now called — is a universal phenomenon as widely 
spread throughout the universe as heat or light. 
Radio-activity is now discovered in nearly every- 
thing; and in a recent paper Professor J. J. Thomson 
has demonstrated its existence in most substances — 
water, sand, clay, brick, etc. 

What becomes of matter when it dissociates? 
Can it be supposed that when atoms disaggregate 
they only divide into smaller parts, and thus form a 
simple dust of atoms ? We shall see that nothing of 
the sort takes place, and that matter which dis- 
sociates dematerializes itself by passing through 
successive phases which gradually deprive it of its 
material qualities until it finally returns to the im- 
ponderable ether whence it seems to have issued. 

The fact once recognized that atoms can dissociate, 
the question arose as to whence they obtained the 
immense quantity of energy necessary to launch into 
space particles with a speed of the same order as 

The explanation in reality was simple enough, 
since it is enough to verify, as I have endeavoured 
to show, that, far from being an inert thing 
only capable of giving up the energy artificially 


supplied to it, matter is an enormous reservoir of 
energy — intra-atomic energy. 

But such a doctrine assailed too many fundamental 
scientific principles established for centuries to be 
at once admitted, and before accepting it various 
hypotheses were successively proposed. Accustomed 
to regard the rigid principles of thermodynamics 
as absolute truths, and persuaded that an isolated 
material system could possess no other energy 
than that supplied from without, the majority 
of physicists long persisted, and some still persist, in 
seeking outside it the sources of the energy mani- 
fested during the dissociation of matter. Naturally, 
they failed to discover it, since it is within, and not 
without, matter itself. 

The reality of this new form of energy, of this 
intra-atomic energy of which I have unceasingly 
asserted the existence from the commencement 
of my researches, is in no way based on theory, but 
on experimental facts. Though hitherto unknown, 
it is the most powerful of known forces, and probably, 
in my opinion, the origin of most others. Its existence, 
so much contested at first, is more and more generally 
accepted at the present time. 

From the experimental researches which I have 
detailed in various memoirs and which will be 
summarized in this work, the following propositions 
are drawn : — 

1. Matter, hitherto deemed indestructible, vanishes 
slowly by the continuous dissociation of its component 

2. The products of the dematerialization of matter 
constitute substances placed by their properties between 
ponderable bodies and the imponderable ether — that is to say, 


between two worlds hitherto considered as widely 

3. Matter, formerly regarded as inert and} only able 
to give back the energy originally supplied to it, is, on the 
other hand, a colossal reservoir of energy — intra-atomic 
energy — which it can expend without borrowing anything 
from without, 

4. It is from the intra-atomic energy manifested during 
the dissociation of matter that most of the forces in the 
universe are derived, and notably electricity and solar 

5. Force and matter are two different forms of one 
and the same thing. Matter represents a stable form 
of intra-atomic energy; heat, light, electricity, etc., 
represent instable forms of it. 

6. By the dissociation of atoms — that is to say, by the de- 
materialization of matter, the stable form of energy termed 
matter is simply changed into those unstable forms known 
by the names of electricity, light, heat, etc. ^ 

7. The. law of evolution applicable to living beings is 
also applicable to simple bodies ; chemical species are no 
more invariable than are living species. 

For the examination of these several propositions a 
large part of this work will be reserved. Let us in this 
chapter take them as proved and seek at once the 
changes they bring about in our general conception of 
the mechanism of the universe. The reader wall thus 
appreciate the interest presented by the problems to 
which this volume is devoted. 

§ 2. Matter and Force. 

The problem of the nature of matter and of force 
is one of those which have most exercised the 
sagacity of scholars and philosophers. Its complete 


solution has always escaped us because it really implies 
the knowledge, still inaccessible, of the First Cause 
of things. The researches I shall set forth cannot 
therefore allow us to completely solve this great 
question. They lead, however, to a conception of 
matter and energy far different from that in vogue at 
the present day. 

When we study the structure of the atom, we shall 
arrive at the conclusion that it is an immense 
reservoir of energy solely constituted by a system 
of imponderable elements maintained in equilibrium 
by the rotations, attractions and repulsions of its 
component parts. From this equilibrium result the 
material properties of bodies such as weight, form, 
and apparent permanence. Matter also represents 
movement, but the movements of its component 
elements are confined within a very restricted space. 

This conception leads us to view matter as a 
variety of energy. To the known forms of energy — 
heat, light, etc. — there must be added another — 
matter, or intra-atomic energy. It is characterized 
by its colossal greatness and its considerable ac- 
cumulation within very feeble volume. 

It follows from the preceding statements that by 
the dissociation of atoms, one is simply giving to the 
variety of energy called matter a different form — such 
as, for example, electricity or light. 

We will endeavour to give an account of the forms 
under which intra-atomic energy may be condensed 
within the atom, but the existence of the fact itself 
has a far greater importance than the theories it 
gives rise to. Without pretending to give the defini- 
tion so vainly sought for of energy, we will content 
ourselves with stating that all phenomenality is 


nothing but a transformation of equilibrium. When 
the transformations of equilibrium are rapid, we call 
them electricity, heat, light, etc.; when the changes 
of equilibrium are slower, we give them the name of 
matter. To go beyond this we must wander into 
the region of hypothesis and admit, as do several 
physicists, that the elements of which the aggregate 
is represented by forces in equilibrium, are consti- 
tuted by vortices formed in the midst of ether. 
These vortices possess an individuality, formerly 
supposed to* be eternal, but which we know now 
to be but ephemeral. The individuality disappears, 
and the vortex dissolves in the ether as soon as the 
forces which maintain its existence cease to act. 

The equilibria of these elements of which the 
aggregate constitutes an atom, may be compared 
to those which keep the planets in their orbits. 
So soon as they are disturbed, considerable energies 
manifest themselves, as they would were the earth 
or any other planet stayed in its course. 

Such disturbances in planetary systems may be 
realized, either without apparent reason, as in very 
radio-active bodies when, for divers reasons, thiey 
have reached a certain degree of instability, or arti- 
ficially, as in ordinary bodies when brought under 
the influence of various excitants — heat, light, etc. 
These excitants act in such cases like the spark on a 
mass of powder — that is to say, by freeing quantities 
of energy greatly in excess of the very slight cause 
which has determined their liberation. And as 
the energy condensed in the atom is immense in 
quantity, it results from this that to an extremely 
slight loss in matter there corresponds the creation of 
an enormous quantity of energy. 


From this standpoint we may say of the various 
forms of energy resulting from the dissociation of 
material elements, such as heat, electricity, light, 
etc., that they represent the last stages of matter 
before its disappearance into the ether. 

If, extending these ideas, we wish to apply 
them to the differences presented by the various 
simple bodies studied in chemistry, we should say 
that one simple body only differs from another by 
containing more or less intra-atomic energy. If we 
could deprive any element of a sufficient quantity of 
the energy it contains, we should succeed in com- 
pletely transforming it. 

As to the necessarily hypothetical origin of the 
energies condensed within the atom, we will seek for 
it in a phenomenon analogous to that invoked by 
astronomers to explain the formation of the sun, and 
of the energies it stores up. To their minds this 
formation is the necessary consequence of the con- 
densation of the primitive nebula. If this theory be 
valid for the solar system, an analogous explanation 
is equally so for the atom. 

The conceptions thus shortly summed up in no 
way seek to deny the existence of matter, as 
metaphysics has sometimes attempted to do. They 
simply clear away the classical duality of matter and 
energy. These are two identical things under 
different aspects. There is no separation between 
matter and energy, since matter is simply a stable 
form of energy and nothing else. 

It would, no doubt, be possible for a higher in- 
telligence to conceive energy without substance, for 
there is nothing to prove that it necessarily requires 
a support; but such a conception cannot be attained 


by US. We can only understand things by fitting 
them into the common frame of our thoughts. 
The essence of energy being unknown, we are 
compelled to materialize it in order to enable us 
to reason thereon. We thus arrive — but only for 
the purposes of demonstration — at the following 
definitions: — Ether and matter represent entities of 
the same order. The various forms of energy: 
electricity, heat, light, matter, etc., are its manifesta- 
tions. They only differ in the nature and the stability 
of the equilibria formed in the bosom of the ether. 
It is by those manifestations that the universe is 
known to us. 

More than one physicist, the illustrious Faraday 
especially, has endeavoured to clear away the duality 
existing between matter and energy. Some philo- 
sophers formerly made the same attempt, by pointing 
out that matter was only brought home to us by the 
intermediary of forces acting on our senses. But all 
arguments of this order were considered, and rightly, 
as having a purely metaphysical bearing. It was 
objected to them that it had never been possible 
to transform matter into energy, and that this latter 
was necessary to animate the former. Scientific 
principles, considered assured, taught that Nature 
was a kind of inert reservoir incapable of possessing 
any energy save that previously transmitted to it. It 
could no more create it than a reservoir can create 
the liquid it holds. Everything seemed then to point 
out that Nature and Energy were irreducible things, 
as independent one of the other as weight is of 
colour. It was therefore not without reason that 
they were taken as belonging to two very different 


There was, no doubt, some temerity in taking up 
anew a question seemingly abandoned for ever. I 
Jiave only done so because my discovery of the 
universal dissociation of matter taught me that the 
atoms of all substances can disappear without return 
by being transformed into energy. The transforma- 
tion of matter into energy being thus demonstrated, 
it follows that the ancient duality of Force and 
Matter must disappear. 

§ 3. Consequences of this Principle of the Vanishing 

of Matter. 

The facts summed up in the preceding pages show 
that matter is not eternal, that it constitutes an 
enormous reservoir of forces, and that it disappears 
by transforming itself into other forms of energy 
before returning to what is, for us, nothingness. 

It can therefore be said that if matter cannot be 
created, at least can it be destroyed without return. 
For the classical adage: "Nothing is created, nothing 
is lost,"^ must be substituted the following: — Nothing 
is created, but everything is lost. The elements of a 
substance which is burned or sought to be annihi- 
lated by any other means are transformed, but they 
are not lost, for the balance affords proof that their 
weight has not varied. The elements of atoms 
which are dissociated, on the contrary, are irrevocably 
destroyed. They lose every quality of matter, in- 
cluding the most fundamental of them all — weight. 
The balance no longer detects them. Nothing can 
recall them to the state of matter. They have 
vanished in the -immensity of the ether which fills 
space, and they no longer form part of our universe, 

* Attributed to Lavoisier. — F. L, 


The theoretical importance of these principles is 
considerable. At the time when the ideas I am 
upholding were not yet defensible, several scholars 
took pains to point out how far the time- 
honoured doctrine of the everlasting nature of matter 
constituted a necessary foundation for science. Thus, 
for instance, Herbert Spencer in one of the chapters 
of First Principles,'^ headed " Indestructibility of 
Matter," which he makes one of the pillars of his 
system, declares that, " Could it be shown, or could 
it with reason be supposed, that Matter, either in its 
aggregates or in its units, ever becomes non-existent, 
it would be needful either to ascertain under what 
conditions it becomes non-existent, or else to confess 
that true Science and Philosophy are impossible." 
This assertion certainly seems too far-reaching. 
Philosophy has never found any difficulty in adapting 
itself to new scientific discoveries. It follows, but 
does not precede them. 

It is not only philosophers who declare the im- 
possibility of assailing the dogma of the indestructi- 
bility of matter. But a few years ago the learned 
chemist Naquet, then Professor at the Faculty de 
M6decine of Paris, wrote — " We have never seen the 
ponderable return to the imponderable. In fact, the 
whole science of chemistry is based on the law that 
such a change does not occur; for, did it do so, good- 
bye to the equations of chemistry ! " 

Evidently, if the transformation of the ponderable 
into the imponderable were rapid, not only must we 
give up the equations of chemistry, but also those 
of mechanics. However, from the practical point of 
view, none of these equations are yet in danger, for 

^ Sixth ed. (1900), Part II., chap, iv., p. 153. — F. I* 


the destruction of matter takes place so slowly that 
it is not perceptible with the means of observation 
formerly employed. Losses in weight under the 
hundredth part of a milligramme being imperceptible 
by the balance, chemists need not take them into 
account. The practical interest of the doctrine of 
the vanishing of matter, by reason of its transfor- 
mation into energy, will only appear when means 
are found of accomplishing with ease the rapid dis- 
sociation of substances. When that occurs, an 
almost unlimited source of energy will be at man's 
disposal gratis, and the face of the world will be 
changed. But we have not yet reached this point. 

At the. present time, all these questions have only 
a purely scientific interest, and are for the time as 
much lacking practical application as was electricity 
in the time of Volta. But this scientific interest is 
considerable, for these new notions prove that the 
only elements to which science has conceded duration 
and fixity are, in reality, neither fixed nor durable. 

Everybody knows that it is easy to deprive matter 
of all its attributes, save one. Solidity, shape, colour, 
chemical properties easily disappear. The very 
hardest body can be transformed into an invisible 
vapour. But, in spite of every one of these changes, 
the mass of the body as measured by its weight 
remains invariable, and always reappears. This in- 
variability constituted the one fixed point in the 
mobile ocean of phenomena. It enabled th^ 
chemist, as well as the physicist, to follow matter 
through its perpetual transformations, and this is 
why they considered it as something mobile but 

It is to this fundamental property of the invari-* 


ability of the mass that we had always to come back. 
Philosophers and scholars long ago gave up seeking 
an exact definition of matter. The invariability of 
the mass of a given quantity of substance — that is to 
say, its coefficient of inertia measured by its weight, 
remained the sole irreducible characteristic of matter. 
Outside this essential notion, all we could say of 
matter was that it constituted the mysterious and 
ever-changing element whereof the worlds and the 
beings who inhabit them were formed. 

The permanence and, therefore, the indestructi- 
bility of mass, which one recognizes throughout the 
changes in matter, being the only characteristic by 
which this great unknown conception can be grasped, 
its importance necessarily became preponderant. 
On it the edifices of chemistry and mechanics have 
been laboriously built up. 

To this primary notion, however, it became 
necessary to add a second. As matter seemed in- 
capable by itself of quitting the state of repose, 
recourse was had to various causes, of unknown 
nature, designated by the term forces, to animate it. 
Physics counted several which it formerly clearly 
distinguished from each other, but the advance in 
science finally welded them into one great entity. 
Energy y to which the privilege of immortality was 
likewise conceded. 

And it is thus that, on the ruins of former 
doctrines and after a century of persistent efforts, 
there sprang up two sovereign powers which seemed 
eternal — matter as the fundamental woof of things, 
and energy to animate it. With the equations 
connecting them, modern science thought it could 
explain all phenomena. In its learned formulas all the 



secrets of the universe were enclosed. The divinities 
of old time were replaced by ingenious systems of 
differential equations. 

These fundamental dogmas, the bases of modern 
science, the researches detailed in this work tend to 
destroy. If the principle of the conservation of 
energy — which, by-the-by, is simply a bold general- 
ization of experiments made in very simple cases— 
likewise succumbs to the blows which are already 
attacking it, the conclusion must be arrived at that 
nothing in the world is eternal. The great divinities 
of science would also be condemned to submit to that 
invariable cycle which rules all things — birth, growth, 
decline, and death. 

But if the present researches shake the very 
foundations of our knowledge, and in consequence 
our entire conception of the universe, they are far 
from revealing to us the secrets of this universe. 
They show us that the physical world, . which 
appeared to us something very simple, governed by a 
small number of elementary laws, is, on the contrary, 
terribly complex. Notwithstanding their infinite 
smallness, the atoms of all substances — those, for 
example, of the paper on which these lines are 
written — now appear as true planetary systems, guided 
in their headlong speed by formidable forces of the 
laws of which we are totally ignorant. 

The new routes which recent researches open out 
to the investigations of inquirers are yet hardly 
traced. It is already much to know that they exist, 
and that science has before it a marvellous world to 



What brought into prominence the facts and prin- 
ciples summarized in the preceding chapter which 
will be unfolded in this work? This I will now 
proceed to show. The genesis of a discovery is 
rarely spontaneous. It only appears so because the 
difficulties and the hesitations which most often 
surround its inception are generally unnoticed. 

The public troubles itself very little with the way 
in which inventions are made, but psychologists will 
qertainly be interested by certain sides of the follow- 
ing account.^ In fact, they will find therein valuable 
documents on the birth of beliefs, on the part 
played, even in laboratories, by suggestions and 
illusions, and finally on the preponderant influence 
of prestige considered as a principal element of 

My researches preceded, in their beginning, all 
those carried out on the same lines. It was, in fact, 
in 1896 that I caused to be published in the Comptes 
Rendus de VAcademie des Sciences, solely for the 
purpose of establishing priority, a short notice 

'^ In order not to lengthen this history unduly I do not give here any 
of the texts on which it is based. The reader will find them at the end 
of the book. 



summing up the researches I had been making for two 
years, whence it resulted that light falling on bodies 
produced radiations capable of passing through 
material substances. Unable to identify these radia- 
tions with anything known, I pointed out in the 
same note that they must probably constitute some 
unknown force — an assertion to which I have often 
returned. To give it a name I called this radiation 
black light (lumiere noire). 

At the commencement of my experiments I per- 
force confused dissimilar things which I had to 
separate one after the other. In the action of light 
falling on the surface of a body there can be observed, 
in fact, two very distinct orders of phenomena: — 

1. Radiations of the same family as the cathode 
rays. They are incapable of refraction or of polariza- 
tion, and have no kinship with light. These are the 
radiations which the so-called radio-active substances, 
such as uranium, constantly emit abundantly and 
ordinary substances freely. 

2. Infra-red radiations of great wave-length which, 
contrary to all that has hitherto been taught, pass 
through black paper, ebonite, wood, stone, and, in 
fact, most non-conducting substances. They are 
naturally capable of refraction and polarization. 

It was not very easy to dissociate these various 
elements at a time when no one supposed that a 
large number of bodies, considered absolutely opaque, 
were, on the contrary, very transparent to the in- 
visible infra-red light, and when the announcement 
of the experiment of photographing a house in two 
minutes and in the dark-room through an opaque 
body would have been deemed absurd. 

Without losing sight of the study of metallic 


radiations, I gave up some time to the examination 
of the properties of the infra-red.^ This examination 
led me to the discovery of invisible luminescence, a 
phenomenon which had never been suspected, and 
enabled me to photograph objects kept in darkness 
for eighteen months after they had seen the light. 

These researches terminated, I was able to proceed 
with the study of metallic radiations. 

It was at the commencement of the year 1897 that 
I announced in a note published in the Comptes 
Rendus de V Academic des Sciences, that all bodies 
struck by light emitted radiations capable of render- 
ing air a conductor of electricity.^ 

A few weeks later I gave, also in the Comptes 
Rendus, details of quantitative experiments serving 
to confirm the above, and I pointed out the analogy 
of the radiations emitted by all bodies under the 
action of light with the radiations of the cathode 
ray family, an analogy which no one till then had 

It was at the same period that M. Becquerel 
published his first researches. Taking up the 
forgotten experiments of Niepce de Saint- Victor, and 
employing, like him, salts of uranium, he showed, as 
the latter had already done, that these salts emitted, 

^ In order not to confuse things which differ, I have reserved the 
term lumiire twire for these radiations. They Mill be examined in 
another volume devoted to the study of energy. Their properties 
differ considerably from those of ordinary light, not only by their 
invisibility, an unimportant characteristic due solely to the structure of 
the eye, but by absolutely special properties — that, for instance, of 
passing through a great number of opaque bodies and of acting in an 
exactly contrary direction to other radiations of the spectrum. 

* This property is still the most fundamental characteristic of radio- 
active bodies. It Was by working from this only that radium and 
polotiium were isolated. 


in darkness, radiations able to act on photographic 
plates. Carrying this experiment farther than his 
predecessor, he established the fact that the emission 
seemed to persist indefinitely. 

Of what did these radiations consist ? Still under 
the influence of the ideas of Niepce de Saint- Victor, 
M. Becquerel thought at first that it was a question 
of what Niepce termed "stored-up light" {lumiere 
emmagasinee) — that is to say, a kind of invisible 
phosphorescence, and, to prove it, he started experi- 
ments described at length in the Comptes Rendus d^ 
V Academic des Sciences, which induced him to think 
that the radiations emitted by uranium were 
refracted, reflected, and polarized. 

This point was fundamental. If the emissions of 
uranium could be refracted and polarized, it was 
evidently a question of radiations identical with light 
and simply forming a kind of invisible phos- 
phorescence. • If this refraction and polarization 
had no existence, it was a question of something 
totally different and quite unknown. 

Not being able to fit in M. Becquerel's experiments 
with my own, I repeated them with diff'erent ap- 
paratus, and arrived at the conclusion that the 
radiations of uranium were not in any way polarized. 
It followed then that we had before us not any form 
of light, but an absolutely new thing, constituting, as 
I had asserted at the beginning of my researches, a 
new force: "The properties of uranium were there- 
fore only a particular case of a very general law." It 
is with this last conclusion that I terminated one of 
my notes in the Comptes Rendus de V Academic des 
Sciences of 1897. 

For nearly three years I was absolutely alone in 


maintaining that the radiations of uranium could 
not be polarized. It was only after the experiments 
of the American physicist, Rutherford,' that M. 
Becquerel finally recognized that he had been mis- 

It will be considered, I think, very curious and one 

Apparatut eiiip'oyed in iS(/i 
by Giti/ave Le Boa tg demon- 
ilrale, fy the abseiiri of polar- 
ixaliim, that Iht radialioiis 
emilied hy salts of uranium 
are not invisib.'c /i^ht. 

One of these 13 Ihe classic 
meihwl of plaiesof teuimaline 
wiih crossetl axes, and i% loo 
well knonn foi any desciiption 
of it to be given here. It only 

difieri fiom the one with Tia. I. 

which M. Beciuerel thought 
he had demonstrated the po- 
lariialion of the uianium rays, 
in having the toiumalines 
flamed in a thick strip of 
metal so as to precent the 
uranium emanation from c'lirg 
round them. The second ap- 
paratus wa3 contrived l>y me , 
fat ihe purpose of vcrifjing 
Ihe negaiive results obi.ii.icd 

by means of the tourmalines. Fig. 3. 

It is composed of a strip of 

metal in which very fine lines have been cut and coveied over with 
Iceland «par. If this be interposed lietween a source of visible or 
invisible light and a photographic plate, we obtain, tbtough the double 
refraction, a duplication of the lines which indicates ihe polaiiialion of 
the emerging rays. This du|ilieation is very clearly seen in the photo- 
graph of the apparatus here reproduced, which has been taken in 
ordinary light. 

' Piofessor Rutherford is a Canadian, and holds the Mac^ooald 
chait of Fhyiics at McGUl University, Montreal.— F. L> 


of the most instructive chapters in the history of 
science that for three years not one single physicist 
was to be met with in the whole world who thought 
of repeating — though they were extraordinarily simple 
— the experiments of M. Becquerel on the refraction, 
reflection, and polarization of the uranium rays. On 
the contrary, the most eminent published ingenious 
theories to explain this very refraction, reflection, 
and polarization. 

It was a new version of the story of the child with 
the golden tooth on which the scholars of the day 
wrote important treatises, till one day it occurred to 
a sceptic to go to see if the said child was really 
born with a golden tooth. It will be difficult, after 
such an example, to deny that, in scientific matters, 
prestige forms the essential element in conviction. 
We must therefore not scoff too much at those in 
the Middle Ages who knew no other sources of 
demonstration than the statements of Aristotle. 

Leaving to its fate the doctrine which for several 
years I alone upheld, I continued my researches, 
enlarged the circle of my investigations, and showed 
that similar radiations arise, not only under the action 
of light, but also under very varying influences, 
chemical reaction especially. It became therefore 
more and more evident that the radiations of uranium 
were only, as I said from the very first, a particular 
case of a very general law. 

This general law, which I have not ceased to 
study, is as follows: — Under divers influences, light, 
chemical reaction, electric action, and often even, 
spontaneously, the atoms of simple bodies, as well 
as those of compound bodies, dissociate and emit 
effluves of the same family as the cathode rays. 


This generalization is at the present day almost 
universally admitted, but the preceding statement of 
facts shows that it needed some courage to formulate 
it for the first time. Who could have supposed any 
relationship between the radiations of uranium and 
any effluves whatever, cathodic or otherwise, since 
nearly all physicists then admitted, on M. Becquerel's 
authority, the polarization and the refraction of these 

When the question as to polarization was definitely 
settled, it took but little time to establish the correct- 
ness of the facts stated by me. But it was only after 
the German physicists, Giesel, Meyer, and Schweidler, 
discovered, in 1899, that tbe emissions of radio- 
active bodies were, like the cathode rays, capable of 
deviation by a magnet, that the idea of a probable 
analogy between all these phenomena began to 
spread. Several physicists then took up this study, 
the importance of which increased day by day. 
New facts arose on all sides, and the discovery 
of radium by Curie gave a great impetus to these 

M. de Heen, Professor of Physics at the University 
of Li6ge, and Director of the celebrated Institute of 
Physics in that town, was the first to accept in its 
entirety the generalization I had endeavoured to 
establish. Having taken up and developed my ex- 
periments, he declared in one of his papers that in 
point of importance they were on a par with the 
discovery of the X rays. They were the origin of 
numerous researches on his part, which led to 
remarkable results. The movement once started, 
it had to be followed up. On all sides radio- 
activity was sought for, and it was discovered 


everywhere. The spontaneous emission is often 
very weak, but becomes considerable in substances 
placed under the influence of various excitants^light, 
heat, etc. All physicists are now. agreed in classing 
in the same family the cathode rays and the emissions 
from uranium, radium, and bodies dissociated by 
light, heat, and the like. 

If, notwithstanding my assertions and my experi- 
ments, these analogies were not at once accepted, it 
is because the generalization of phenomena is at 
times much more difficult to discover than the facts 
from which this generalization flows. It is, however, 
from these generalizations that scientific progress is 
derived. " Every great advance in the sciences," 
said the philosopher Jevons, "consists of a vast 
generalization revealing deep and subtle analogies." 

The generality of the phenomenon of the dissocia- 
tion of matter would have been noticed much sooner 
if a number of known facts had been closely 
examined, but this was not done. These facts, 
besides, were spread over very different chapters of 
physics. For example, the loss of electricity occa- 
sioned by ultra-violet light had long been known, 
but one little thought of connecting the fact with the 
cathode rays. More than fifty years ago Niepce 
de Saint-Victor saw that, in the dark, salts of 
uranium caused photographic impressions for several 
months; but as this phenomenon did not seem to be 
connected with any known fact, it was put on one 
side. For a hundred years the gases of flaihes had . 
been observed to discharge electrified bodies without 
any one attempting to examine the cause of this 
phenomenon. The loss of electric charges through 
the influence of light had been pointed out several 


years before, but it was regarded as a fact peculiar to 
a few metals, without any suspicion of how general 
and important it was.^ 

All these phenomena and many others, such as 
electricity and solar heat, are very dissimilar in 
appearance, but are the consequences of the same 
fact — namely, the dissociation of matter. The 
common link which connects them appeared clearly 
directly we established that the dissociation of matter 
and the forms of energy which result from it are to 
be ranked among the most widely spread natural 

The establishment of the fact of the dissociation of 
matter has allowed us to penetrate into an unknown 
world ruled by new forces, where matter, losing its 
properties as matter, becomes imponderable in the 
balance of the chemist, passes without difficulty 
through obstacles, and possesses a whole series of 
unforeseen properties. 

I have had the satisfaction of seeing, while still 
alive, the recognition of the facts on which I 
based the theories which follow. For a long time I 
had given up all such hope, and more than once had 
thought of abandoning my researches. They had, in 
fact, been rather badly received in France. Several 
of the notes sent by me to the Academy of Sciences 
provoked absolute storms. The majority of the 
members of the Section of Physics energetically pro- 

^ It is precisely in ihe interpretation of these early facts, which no 
one had ever thought of connecting with radio-active phenomena, that 
the difficulty lay. This is what Mr. VVhetham has entirely failed to 
grasp in his review of this work published in Nature, The perusal 
of the volume in which this specialist has endeavoured to popularize 
the researches on radio-activity will show, moreover, that he has 
failed to comprehend these phenomena. 


tested, and the scientific press joined in the chorus. 
We are so hierarchized, so hypnotized and tamed by 
our official teaching, that the expression of in- 
dependent ideas seems intolerable. To-day, when my 
ideas have slowly filtered into the minds of physicists, 
it would be ungracious to complain of their criticisms 
or the silence of most of them towards me. Sufficient 
for me is it that they have been able to avail them- 
selves of my researches. The book of nature is a 
romance of such passionate interest that the pleasure 
of spelling out a few pages repays one for the trouble 
this short decipherment often demands. I should 
certainly not have devoted over eight years to these 
very costly experiments had I not at once grasped 
their immense philosophical interest and the profound 
perturbation they would finally cause to the funda- 
mental theories of science. 

. With the discovery of the universal dissociation 
of matter is linked that of intra-atomic energy, by 
which I have succeeded in explaining the radio- 
active phenomena. The second was the consequence 
of the first-named discovery. 

The discovery of intra-atomic energy cannot, how- 
ever, be quite assimilated to that of the universality 
of the dissociation of matter. This universal dissocia- 
tion is a fact, the existence of intra-atomic energy is 
only an interpretation. This interpretation, besides, 
was necessary, for, after having tried several 
hypotheses to explain the radio-active phenomena, 
nearly all physicists have finally fallen in with 
the explanation I proposed when I announced that 
science was face to face with a new force hitherto 
entirely unknown. 

It may interest the reader to know how the 


researches which have thus- been briefly recorded 
were received in various countries. 

It was especially abroad that they created a deep 
impression. In France, they met with a hostility 
which was not, however, unanimous, as will be seen 
by this extract from a study published by M. Dastre, 
Professor at the Sorbonne and a member of the 
Institut : — 

" In the course of five years a fairly long journey has been 
covered on the road towards the generalization of the fact of 
radio-activity. Starting with the idea of a property specific to 
uranium, we have reached the supposition of a well-nigh universal 
natural phenomenon. 

" It is right to recall that this result was predicted with 
prophetic perspicacity by Gustave Le Bon. From the outset 
this scholar endeavoured to show that the action of light, 
certain chemical reactions, and lastly the action of electricity, 
call forth the manifestation of this particular mode of energy. 
. . . Far from being rare, the production of these rays is un- 
ceasing. Not a sunbeam falls on a metallic surface, not an electric 
spark fiashes, not a discharge takes place, not a single body be- 
comes incandescent, without the appearance of a pure or trans- 
formed cathode ray. To Gustave Le Bon must be ascribed the 
merit of having perceived from the first the great generality of 
this phenomenon. Even though he has used the erroneous 
term of Luinilre noire^ he has none the less grasped the 
universality and the principal features of this product. He has 
above all set the phenomenon in its proper place by transferring 
it from the closet of the physicist into the grand laboratory of 
nature." (Revue des Deux Mondes^ 1901.) 

In one of the annual reviews on physical studies 
which he publishes annually, Professor Lucien 
Poincar6 has very clearly summarized my researches 
in the following lines: — 

" M. Gustave Le Bon, to whom we owe numerous publications 
relating to the phenomena of the emission by matter of various 


radiations, and who was certainly one of the first to think 
that radio-activity is a general phenomenon of nature, supposes 
that under very different influences, light, chemical action, 
electrical action, and often even, spontaneously, the atoms of 
simple bodies dissociate and emit effluves of the same 
family as the cathode and X rays; but all these manifestations 
would be particular aspects of an entirely new form of energy, 
quite distinct from electrical energy, and as widely spread 
throughout nature as heat. M. de Keen adopts similar ideas." 
{Revue GMrale des Sciences^ January 1903.) 

I have only one fragment of a phrase to correct 
in the above lines. The eminent scholar says that 
I was " one of the first " to show that radio-activity 
is a universal phenomenon. This should read 
" the first." It suffices to turn to the texts and to 
their dates of publication to be convinced of this fact.^ 

It is natural enough that one should not be a 
prophet in one's own country. It is sufficient to 
be a little of one elsewhere. The importance of the 
results brought to light by my researches was very 
quickly understood abroad. Out of the different 
studies they called forth, I shall confine myself to 
reproducing a few fragmeigis. 

The first is a portion of the preamble to four 
articles devoted to my experiments in the English 
Mechanic : — ^ 

^ My first memoir on the radio-activity of all bodies under the action 
of light appeared in the Revtte Scientifique of May 1897. The one 
on radio-activity by chemical reaction in April 1900. The memoir 
demonstrating the spontaneous radio-activity of primary bodies appeared 
— in the same review — in November 1902. The first experiments 
by means of which physicists sought to prove that radio-activity could 
be detected in substances other than uranium, thorium, and radium 
were published by Strutt, McLennan, Burton, etc., only between June 
and August 1903. 

2 The issues from January to April 1903. 


"During six years Gustave Le Bon has continuied his re- 
searches on certain radiations which he at first termed Lumihe 
noire. He scandalized orthodox physicists by his audacious 
assertion that there existed something which had been quite 
unknown. However, his experiments decided other searchers 
to verify his assertions, and many unforeseen facts were dis- 
covered. Rutherford in America, Nodon in France, de Heen 
in Belgium, Lenard in Austria, Elster and Geitel in Switzerland 
have successfully followed in the lines of Gustave - Le Bon. 
Summing up to-day the experiments made by him for the last 
six years, Gustave Le Bon shows that he has discovered a new 
force in nature which manifests itself in all bodies. His experi- 
ments cast a vivid light on such mysterious subjects as the 
X rays, radio-activity, electrical dispersion, the action of ultra- 
violet light, etc. Classical books are silent on all these subjects, 
and the most eminent electricians know not how to explain 
these phenomena." 

The second of the articles to which I have above 
alluded is one in The Academy of the 6th December, 
1902, under this heading: "A New Form of 

"Hardly anything is more marked than the way in which 
the ideas of men of science with regard to force and matter 
have completely changed during the last ten years. . . . The 
atomic theory that ev«ry scrap of matter could be divided 
in the last resort into atoms each in itself indivisible and com- 
bining among themselves only in fixed proportions, was then a 
law of scientific faith, and led to pronouncements like those of 
a late President of the Chemical Society, who informed his 
bearers in his annual allocution that the age of discovery in 
chemistry was closed, and that henceforth we had better devote 
ourselves to a thorough classification of chemical phenomena. 
But this prediction . . . was no sooner uttered than it was 
falsified. There came before us Mr. (not then Sir William) 
Crookes' discovery of what he called * radiant matter,* . . . 
then Rontgen's rays . . . until now M. Gustave Le Bon . . . 
assures us that these new ideas are not several things but one 
thing, and that they all of them point *q a form of matter 


spread throughout the world indeed, but so inconceivably 
minute that it becomes not matter but force. . . . The con- 
sequences of the final acceptance of [M. Le Bon's] theory are 
fairly enormous. ... As for chemistry, the whole fabric will be 
demolished at a blow; and we shall have a tabula rasa on 
which we may write an entirely new system wherein matter will 
pass through matter, and 'elements' will be shown to be only 
differing forms of the same substance. But even this will be. 
nothing compared with the results which will follow the bridging 
of the space between the material and the immaterial which. 
M. Le Bon anticipates as the result of his discoveries, and 
which Sir William Crookes seems to have foreshadowed in his 
address to the Royal Society upon its late reception of the 
Prince of Wales." 

I will add to these quotations a passage from 
the divers articles which M. de Heen, Professor 
of Physics at the University of Li^ge, has kindly 
devoted to my researches: — 

"The resounding effect produced in the world by the dis- 
covery of the X rays is well knowli, a discovery which was 
immediately followed by one more modest in appearance, but 
perhaps more important in reality — viz., that of Black Light, 
as the result of the researches of Gustave Le Bon. This last 
scholar proved that bodies struck by light, especially metals, 
acquire the faculty of producing rays analogous to the X rays, 
and discovered that this was not simply an exceptional pheno- 
menon, but, on the contrary, one of an order of phenomena as 
common throughout nature as calorific, electricity, and luminous 
manifestations, a thesis which I also have constantly upheld 
from that time." 

But all this is already ancient history. The anger 
which my first researches provoked in France has 
vanished. The staffs of the laboratories formerly so 
hostile have welcomed with sympathetic curiosity 
the first editions of this work. The proof of this I 


have found in several articles, and especially in the 
review by one of the most distinguished young 
scholars of the Sorbonne, of which I give a few 
extracts: — 

"It will be Dr. Le Bon's title to fame that he was the first 
to attack the dogma of the indestructibility of matter, and that 
he has destroyed it within the space of a few years. In 1896 he 
published a short no,te which will mark one of the most im- 
portant dates in the history of science, for it has been the 
starting-point of the discovery of the dissociation of matter. 
... To the already known forms of energy, heat, light, etc., 
another must be added, namely, matter or intra-atomic energy. 
The reality of this new form of energy, which Dr. Le Bon has 
made known to us, rests in no way upon theory, but is deduced 
from experimental fact. Although unknown till now, it is the 
most mighty of known forces, and may even be the origin of 
most of the others. . . . The beginning of Dr. Le Bon's work 
produces in the reader a deep impression ; one feels in it the 
breath of a thought of genius. . . . Dr. Le Bon has been com- 
pared to Darwin. If one were bound to make a comparison, I 
would rather compare him to Lamarck. Lamarck was the first 
to have a clear idea of the evolution of living beings. Dr. Le' 
Bon was the first to recognize the possibility of the evolution of 
matter, and the generality of the radio-activity by which its dis* 
appearance is manifested." ^ 

The reader will, I hope, excuse this short pleading. 
The repeated forgetfulness of certain physicists has 
compelled me to utter it. The new phenomena I 
have discovered have cost me too much labour, too 
much money, and too much annoyance for me not to 
try to keep a firm hold on a prize obtained with so 
much difficulty .2 

* Georges Bohn, Revue des IdeeSy 15th January 1906. 

' It will be considered a curious proof of the narrow and timid 
mentality of some of our French '* Dons" that two of them, namely, 
MM. M. Abraham and P. Langevin, having thought it useful to reprint 



in two huge volumes everyihing that has been written on ionization 
and radio-activity, did not dare to allow the title of any one of my 
memoirs to appear there. Among these last, however, there aie some, 
and notably one on the radio-activity which certain substances acquire 
by chemical reactions so simple as hydration, of which the funda- 
mental and theoretical importance has not escaped some eminent foreign 
physicists, since they have taken the trouble to repeat and develop niy 
experiments at length with due acknowledgment to the author. 

BOOK 11. 




§ I. The Existence of Intra-atomic Energy, 

I HAVE given the name of Intra-atomic Energy to 
the new force, differing entirely from those hitherto 
observed, which is produced by the dissociation 
of matter — that is to say, by the whole series of radio- 
active phenomena. From the chronological point of 
view, I ought evidently to commence by describing 
this dissociation ; but as intra-atomic energy governs 
all the phenomena examined in this^work, it seems 
to me preferable to begin by its study. 

I shall therefore suppose an acquaintance with the 
facts concerning the dissociation of matter which I 
shall set forth later, and shall confine myself at 
present to recalling one of the most fundamental of 
these facts — the emission into space, from bodies 
undergoing dissociation, of immaterial particles ani- 
mated by a speed capable of equalling and even of 
often exceeding a third of the speed of light. That 
speed is immensely superior to any we can produce 
by the aid of the known forces at our disposal. This 



is a point which must be steadily kept in mind from 
the first. A few figures will suffice to make this 
difference evident. 

A very simple calculation shows, in fact, that to 
give a small bullet the speed of the particles emitted 
by matter in process of dissociation would require 
a firearm capable of containing one million 
three hundred and forty thousand barrels of gun- 
powder.^ As soon as the immense speed of the 
particles emitted was measured by the very simple 
methods I describe elsewhere, it became evident that 
an enormous amount of energy is liberated during the 

^ Here are the particulars of this calculation : — 

Determination of the expenditure of energy necessary to give to a 
material mass a speed equal to that of the particles of dissociated matter » 
— If we leave aside the resistance of the air, which would involve com- 
plicated calculations, it is easy to determine the dimensions a material 
mass should possess, to acquire, under the influence of a given ex- 
penditure of energy — that, for instance, employed to launch a bullet — a 
velocity of the order of magnitude of that of the particles of dissociated 
matter. This calculation will at obce show the power of intra-atomic 

The energy developed by an ordinary bullet animated by a speed of 
640 metres per second is given by the formula 

T = i-m V» =12:^ X 640^ = 313 kgm. 

2 2 9.81 ^ ^ x> ^ 

Let us inquire the weight x to be given to a bullet for it, with the same 
quantity of energy, to acquire a speed of 100,000 kilometres per second 

in vacuo. This is 313 = i — ^ x 100,000,000'. By working 

2 9.81 / . & 

out the calculation it is seen that the bullet would require to have a 
weij^ht rather above 6 ten -million ths of a milligramme to equal the speed 
of the particles of dissociated matter, with the powder-charge necessary 
to launch a rifle-bullet. 

With the above data, and knowing that it takes 2.75 gr. of powder 
to throw a Lebel bullet weighing 15 grammes, it is an easy matter to 
calculate that, to give this bullet a speed of 100,000 kilometres per 
second 67 million kilogrammes of powder would be required— thai 
is, 1,340,000 barrels of powder each weighing 50 kilogrammes. 


dissociation of atoms. Physicists then sought in vain 
and many are still seeking the external source of this 
energy. It was understood, in fact, to be a funda- 
mental principle that matter is inert and can only 
give back, in some form or other, the energy which 
has first been supplied to it. The source of the 
energy manifested could therefore only be external. 

When I proved that radio-activity is a universal 
phenomena and not peculiar to a small number of 
exceptional bodies, the question became still more 
puzzling. But, as this radio-activity is above all 
manifested under the influence of external agents — 
light, heat, chemical forces, etc. — it is comprehensible 
that we should seek for the origin of this proved 
energy among these external causes, though there is 
no comparison between the magnitude of the effects 
produced and their supposed causes. As to spon- 
taneously radio-active bodies, no explanation of the 
same order was possible, and this is why the question 
set forth above remained unanswered and seemed to 
constitute an inexplicable mystery. Yet, in reality, 
the solution to the problem is very simple. In order 
to discover the origin of the forces which produce the 
phenomena of radio-activity, one has only to lay aside 
certain classical dogmas. Let us first of all remark 
that it is proved by experiments that the particles 
emitted during dissociation possess identical charac- 
teristics, whatever the substance in question and the 
means used to dissociate it. Whether we take the 
spontaneous emission from radium or from a metal 
under the action of light, or again from a Crookes' 
tube, the particles emitted are similar. The origin 
of the energy which produces the observed effects 
seems therefore to be always the same. Not being 


external to matter, it can only exist within this 

It is this energy which I have designated by the 
term intra-atomic energy. What are its fundamental 
characteristics? It differs from all forces known 
to us by its very great concentration, by its 
prodigious power, and hy the stability of the equili- 
bria it can form. We shall see that, if instead 
of succeeding in dissociating thousandths of a milli- 
gramme of matter, as at present, we could dissociate 
a few kilogrammes, we should possess a source of 
energy compared with which the whole provision of 
coal contained in our mines would represent an 
insignificant total. It is by reason of the magnitude 
of intra-atomic energy that radio-active phenomena 
manifest themselves with the intensity we observe. 
This it is which produces the emission of particles 
having an immense speed, the penetration of 
material bodies; the apparition of X rays, etc., 
phenomena which we will examine in detail in other 
chapters. Let us confine ourselves, for the moment, 
to remarking that effects such as these can be caused 
by none of the forces previously known. The uni- 
versality in nature of intra-atomic energy is one of its 
characteristics most easy to define. We can re- 
cognize its existence everywhere, since we now 
discover radio-activity everywhere. The equilibria 
it forms are very stable, since matter dissociates so 
feebly that for a long time one could believe it to be 
indestructible. It is, besides, the effect produced on 
our senses by those equilibria that we call matter. 
Other forms of energy — light, electricity, etc., are 
characterized by very unstable equilibria. 

The origin of intra-atomic energy is not difficult 


to elucidate, if one supposes, as do the astronomers, 
that the condensation of our nebula suffices by itself 
to explain the constitution of our solar system. It is 
conceivable that an analogous condensation of the 
ether may have begotten the energies contained in 
the atom. The latter may be roughly compared to a 
sphere in which a non-liquefiable gas was com- 
pressed to the' degree of thousands of atmospheres at 
the beginning of the world. 

If this new force — the most widespread and the 
mightiest of all those of nature — has remained 
entirely unknown till now, it is because, in the first 
place, we lacked the reagents necessary for the proof 
of its existence, and then, because the atomic edifice 
erected at the beginning of the ages is so stable, so 
solidly united, that its dissociation — at all events 
by our present means — remains exti«mely slight. 
Were it otherwise the world would long ago have 

But how IS tt that a demonstration so simple as 
tfcat of the existence of intra-atomic energy has not 
been made since the discovery of radio-activity, and 
especially since I have demonstrated the generality 
of this phenomenon ? This can only be explained by 
bearing in mind that it was contrary to all known 
principles to recognize that matter could by itself 
produce energy. Now, scientific dogmas inspire the 
same superstitious fear as did the gods of old, though 
they have at times all their liability to be broken. 

^ 2. Estimate of the Quantity of Intra-atomic Energy 

contained in Matter. 

I have said a few words as to the magnitude of 
intra-atomic energy. Let us now try to measure it. 


The following figures will show that, whatever may 
be the method adopted, we arrive, by measuring the 
energy liberated by a given weight of dissociated 
matter, at totals immensely superior to all those 
obtained by hitherto known chemical reactions — the 
combustion of coal, for example. It is for this 
reason that substances, in spite of the slightness of 
their dissociation, are able to produce during this 
phenomenon the intense effects which I have to 

The different methods in use for measuring the 
speed of the particles of dissociated matter, whether 
radium or any metal whatever, have always given 
nearly the same figures. This speed is almost that of 
light for certain radio-active emissions. For others 
we get a third of that speed. Let us take the lesser 
of these figures, . that of 100,000 kilometres per 
second, and endeavour, on that basis, to calculate 
the energy that would result from the complete 
dissociation of one gramme of any matter we 

Let us take, for instance, a copper one-centime 
piece, weighing, as is well known, one gramme, and 
let lis suppose that by accelerating the rapidity of 
its dissociation we could succeed in totally dis- 
sociating it." 

The kinetic energy possessed by a body in motion 
being equal to half the product of its mass by the 
square of its speed, an easy calculation gives the 
power which the particles of this gramme of matter, 
animated by the speed we have supposed, would 
represent. We have, in fact, 

T = 2:2^ X - X i = 510 thousand 

9.8I; • 2 100,000,000 -" 


millions of kilometres, figures which correspond to 
about six thousand eight hundred million horse-power 
if this gramme of matter were stopped in a second. 
This amount of energy, suitably disposed, would be 
sufficient to work a goods train on a horizontal line 
equal in length to a little over four times and a 
quarter the circumference of the earth.^ 

To send this same train over this distance by 
means of coal would take 2,830,000 kilogrammes, 
which at 24 francs a ton, would necessitate an 
expenditure of about 68,000 francs. This amount of 
68,000 francs represents, therefore, the commercial 
value of the intra-atomic energy contained in a one- 
centime coin. 

What determines the greatness of the above 
figures and makes them at first sight improbable 
is the enormous speed of the masses in play, a 
speed which we cannot approach by any known 
mechanical means. In the factor m V^ the mass of 
one gramme is certainly very small, but the speed 
being immense the effects produced become equally 
immense. A rifle-ball falling on the skin from the 
height of a few centimetres produces no appreciable 
effect in consequence of its slight speed. As soon 
as this speed is increased, the effects become more 
and more deadly, and, with the speed of 1000 mfetres 
per second given by the powder now employed, the 

^ I take, in this calculation, a normal goods train, comprising 40 
trucks of 12 J tons, say, a weight of 500 tons, journeying at a speed of 
36 kilometres per hour on the level, and necessitating a haulage force 
of 6 kilogrammes per ton per second — or 3CXX) kilogrammes for the 500 
tons. The force given out by the engine pulling this train at a speed 
of 36 kilometres would amount to 400 h.p. At the rate of i J kilos of 
coal per unit and per hour, there would \>c consumed in 4,722 hourd 
(duration of the journey) 4,722 x 400 x i. 5 = 2,830,000 kilogrammes. 


bullet will pass through very resistant obstacles. To 
reduce the mass of a projectile matters nothing if one 
arrives at a sufficient increase in speed. This is 
exactly the tendency of modern musketry, which 
constantly reduces the calibre of the bullet but 
endeavours to increase its speed. 

Now the speeds which we can produce are abso- 
lutely nothing compared with those of the particles of 
dissociated matter. We can barely exceed a kilometre 
per second by the means at our disposal, while the 
speed of radio-active particles is 100,000 times 
greater. Thence the magnitude of the effects pro- 
duced. These differences become plain when one 
knows that a body having a velocity of 100,000 kilo- 
metres per second would go from the earth to the 
moon in less than four seconds, while a cannon ball 
would take about live days. 

Taking into account a part only of the energy 
liberated in radio-activity, and by a different method, 
figures inferior to those given above, but still colossal, 
have been arrived at. The measurements of Ctto 
prove that one gramme of radium emits 100 calorie- 
grammes an hour, which would give 876,000 calories 
per annum. If the life of a gramme of radium is 
1000 years, as is supposed, by transforming these 
calories into kilogramm^tres at the rate of 1125 
kilogramm^tres per great calorie, the immensity of 
the figures obtained will readily appear. Necessarily, 
these calories, high as is their number, only represent 
an insignificant part of the intra-atomic energy, since 
the latter is expended in various radiations. 

The fact of the existence of a considerable con- 
densation of energy within the atoms only seems to 
jar on us because it is outside the range of things 


formerly taught us by experience; it should, however, 
be nemarked that, even leaving on one side the facts 
revealed by radio-activity, analogous concentrations 
are daily observable. Is it not strikingly evident, in 
fact, that electricity must exist at an enormous degree 
of accumulation in chemical compounds, since it is 
found by the electrolysis of water that one gramme 
of hydrogen possesses an electric charge of 96,000 
coulombs? One gets an idea of the degree of con- 
densation at which the electricity existed before its 
liberation, from the fact that the quantity above 
mentioned is immensely superior to what we are %ble 
to maintain on the largest surfaces at our disposal. 
Elementary treatises have long since pointed out that 
barely a twentieth part of the above quantity would 
suffice to charge a globe the size of the earth to a 
potential of 6000 volts. The best static machines 

in our laboratories hardly give forth of a cou- 


lomb per second. They would have, consequently, to 
work unceasingly for a little over thirty years to give 
the quantity of electricity contained within the atoms 
of one gramme of hydrogen.^ 

As electricity exists in a state of considerable con- 
centration in chemical compounds, it is evident that 
the atom might have been regarded long since as 
a veritable condenser of energy. To grasp there- 
after the notion that the quantity of this energy must 
be enormous^ it was only necessary to appreciate the 
magnitude of the attractions and repulsions which 

^ They would indeed make this output at tensions of about 50,000 
volts, so that the power produced (volts x amperes) would greatly 
exceed, at the end of thirty years, the power generated by 96,000 
coulombs under a pressure of one volt. 


are produced by the electric charges before us. It is 
curious to note that several physicists have touched 
the fringe of this question without perceiving its con- 
sequences. For example, Cornu pointed out that if it 
were possible to concentrate a charge of one coulomb 
on a very small sphere, and to bring it within one 
centimetre of another sphere likewise having a charge 
of one coulomb, the force created by this repulsion 
would equal 9^^ dynes, or about 9 billions of 

Now, we have seen above that by the dissociation 
of water we can obtain from one gramme of hydrogen 
an electric charge of 96,000 coulombs. It would be 
enough — and this is exactly the hypothesis lately 
enunciated by J. J. Thomson — to dispose the electric 
particles at suitable distances within the atom, to 
obtain, through their attractions, repulsions, and 
rotations, extremely powerful energies in an ex- 
tremely small space. The difficulty was not, there- 
fore, in conceiving that a great deal of energy 
could remain within an atom. It is even surprising 
that a notion so evident was not formulated long since. 

Our calculation of radio-active energy has been 
made within those limits of speed at which ex- 

• * These figures of Cornu*s only give the amount of the force of re- 
pulsion between the two spheres. We can calculate the amount of 
power such a force as the above would yield in given conditions of time 
and space. If we suppose that the distance between the two spheres 
passes under ihe influence of the force in question at from i centimetre 
to I decimetre in i second, the power produced will be represented in 
C. G. S. units by the formula — 

T=/ Fds = 9.ioi8 / 21 =8.1x10" ergs. 

Converted- into kilogrammetres, this formula gives 82 thousand million 
and a half kilogrammetres, or over one thousand millions h.p. per 


periments show that the inertia of these particles 
does not sensibly vary, but it is possible that one 
cannot assimilate their inertia — though this is 
generally done — to that of material particles, and 
then the figures given might be different. But 
they would none the less be extremely high. 
Whatever the methods adopted and the elements 
of calculation employed — ^velocity of the particles, 
calories emitted, electric attractions, etc. — one arrives 
at figures differing from each other indeed, but all 
extraordinarily high. Thus, for example, Rutherford 
fixes the energy of the a particles of thorium at six 
hundred million times that of a rifle-ball. Other 
physicists who, since the publication of one of my 
papers have gone into the subject, have reached 
figures sometimes very much higher. Assimilating 
the mass of electrons to that of the material particles. 
Max Abraham arrives at this conclusion : " That the 
number of electrons sufiicient to weigh one gramme 
carry with them an energy of 6 x 10^^ joules." Re- 
ducing this figure to our ordinary unit, it will be seen 
to represent about 80,000,000,000 horse-power per 
second, about twelve times greater than the figures 
I found for the energy emitted by one gramme of 
particles with a speed of 100,000 kilomfetres per 

J. J. Thomson also has gone into estimates of the 
magnitude of the energy contained in the atom, 
starting with the hypothesis that the material atom 
is solely composed of electric particles. His figures, 
though also very high, are lower than those just 
given. He finds that the energy accumulated in 
one gramme of matter represents 1.02 X 10^* ergs, 
which would be about 100,000,000,000 kilogram- 


metres.^ These figures only represent, according 
to him, "an exceedingly small fraction" of that 
possessed by the atoms at the beginning and 
gradually lost by radiation. 

§ 3. Forms under which Energy can be Condensed 

in Matter, 

Under what forms can intra-atomic energy exist, 
and how can such colossal forces have been con- 
centrated in very small particles ? The idea of such 
a concentration seems at first sight inexplicable, 
because our ordinary experience tells us that the 
extent of mechanical power is always associated with 
the dimensions of the apparatus concerned in its 
production. A 1000 h.p. engine is of considerable 
volume. By association of ideas we are therefore led 
to believe that the extent of mechanical energy 
implies the extent of the apparatus which produces 
it. But this is a pure illusion consequent on the 
weakness of our mechanical systems, and easy to 
dispel by very simple calculations. One of the 
most elementary formulas of dynamics teaches us 
that the energy of a body of constant size can be 
increased at will by simply increasing its speed. It 

^ Electricity and McUier^ 1904. J. J. Thomson arrives at this figure 
by supposing the atom to be composed of negative electrons distributed 
within a sphere charged with a like quantity of positive electricity, and 
inquires the work necessary to separate them. Calling n the number 
of electrons in the atom (1000 for hydrogen), a the radius of the atom 
(10-^ cm. according to the kinetic theory of gases), e the charge in 
electro-static units of each electron (3.4 x 10-^®), N the number of atoms 

contained in i gramme (10.2 x 10^ x -), we obtain, for the quantity of 

energy contained in i gramme of hydrogen, the formula: 

N ^ — i-= 1.02 X 10'* ergs. 


is therefore possible to imagine a theoretical machine 
composed of the head of a pin turning round in the 
bezel of a ring, which, notwithstanding its smallness, 
should possess, thanks to its rotative force, a mechani- 
cal power equal to that of several thousands of 

To fix our ideas, let us suppose a small bronze 
sphere (density 8.842), with a radius of three milli- 
metres and consequently of one gramme in weight. 
Let us suppose that it rotates in space round one 
of its diameters with an equatorial speed equal to 
that of the particles of dissociated matter (100,000 
kilogrammes per second), and that, by some process 
or other, the rigidity of the metal has been made 
sufficient to resist this rotation. Calculating 'the 
vis viva of this sphere it will be seen to corre- 
spond to 203,873.000,000 kilogrammMres. This is 
nearly the work that 1,510 locomotives averaging 
500 h.p.i apiece would supply in an hour. Such is 

^ I have calculated these figures in the following manner : — 
The vis viva of an invariable solid which turns round an axis at an 
angular speed w is expressed by 

I w^ . w^ 

T =--2 mv'^ = — S mf^^— I 
2, 2 2 

The I designating the moment of inertia of the solid. In order to * 

calculate it, the motion of the solid is brought down to a system of 

rectangular co-ordinates in which the axis of rotation is taken as the 

axis of the s. The moment of inertia I is then given by the following 

formula : — 


m (x^ + y^) dx dy dz 

In the special case under consideration of a homogeneous sphere with 

a radius R and a specific weight P, this integral has a value of 

8 P 
I = — T - R5 
15 ^ 

which gives as the expression of the energy 

4 P 

T = — IT - R« w - 

15 i^ 


the amount of energy that could be contained in a 
very small sphere animated by a rotatory movement 
of which the speed should be equal to that of the 
particles of dissociated matter. If the same little 
ball turned on its own centre with the velocity 
of light (300,000 kilogrammes per second) which 
represents about the speed of the P particles of 
radium, its vis viva would be nine times greater. 
It would exceed 1,800,000,000,000 kilogrammfetres 
and represent the work of one hour by 13,590 
locomotives, a number exceeding all the locomotives 
on all tlie French lines.^ 

It is precisely these excessively rapid movements 
of rotation on their axis and round a centre that the 
elefnents which constitute the atoms seem to possess, 
and it is their speed which is the origin of the 
energy they contain. We have been led to suppose 
the existence of these movements of rotation by 
various mechanical considerations much anterior to 
the discoveries of the present day. These last have 
simply confirmed former ideas •and have re-trans- 

^ Previously, we simply examined the energy of a gramme of dis- 
sociated matter, animated, not with the movement of rotation we have 
just supposed, but with a movement of progression in a straight line 
such as is observed in the emission of cathode rays. 

In this last case the figures were even greater than those I have just 
given for a sphere one gramme in weight turning on its axis with a 
. velocity of loo.cxx) kilometres per second. 

The calculation shows, in fact, that the energy of a sphere in 
rotation represents only 2/5ths of that which would be possessed by the 
same sphere animated by a speed of translation equal to the equatorial 
velocity which was first supposed : — 


This is only a consequence of the well-known fact that the square of 
the radius of gyration of a sphere is 2/5ths of the square of the radius of 
this sphere. 


ferred to the elements of the atom the motion which 
was attributed to the atom itself at a time when it 
was considered indivisible. It is only, no doubt, 
because they possess such velocities of rotation that 
the elements which constitute the atoms can, when 
leaving their orbits under the influence of various 
causes, be launched at a tangent through space with 
the velocities observed in the emissions of particles 
of matter in course of dissociation. 

The rotation of the elements of the atom is more- 
over the very condition of their stability, as it is for 
a tdp or for a gyroscope. When under the influence 
of any cause the speed of rotation falls below a 
certain critical point, the equilibrium of the particles 
becomes unstable, their kinetic energy increases and 
they may be expelled from the system, a phenomenon 
which is the commencement of the dissociation of the 

§ 4. The Utilization of Intra-atomic Energy. 

The last objectioils to the doctrine of intra-atomic 
energy are daily disappearing, and it is now hardly 
contested that matter is a prodigious reservoir of 
energy; while the search for the means of easily 
liberating this energy will surely be one of the most 
important problems of the future. It is important 
to notice that, although the numbers above arrived 
at in various ways point out the existence in matter 
of immense forces — so unforeseen hitherto — they by 
no means imply that these forces are already at our 
disposal. In fact the substances which dissociate 
quickest, like radium, only disengage very minute 
quantities of energy. All those millions of kilogram- 
metres which a simple gramme of matter contains 



amount in reality to very little if, to obtain them, 
we have to wait millions of years. Suppose a 
strong box containing several thousand millions of 
gold dust to be closed by a mechanism which only 
permits the daily extraction of a milligramme of the 
precious metal. The owner of that strong box, 
notwithstanding his great wealth, would be in 
reality very poor, and would remain so, so long as 
his efforts to discover the secret of the mechanism 
by which he could open it were unsuccessful. 

This is our position as regards the forces enclosed 
in matter. But, to succeed in capturing them, it 
was first necessary to be acquainted with their exist- 
ence, and of this one had not the least idea a few 
years ago. It was even thought very certain that 
they did not exist. But shall we succeed in easily 
liberating the colossal power which the atoms conceal 
in their bosom ? No one can foresee this. No more 
could any one say in the days of Galvani that the 
electrical energy which enabled him to move with 
difficulty the legs of frogs and to attract small scraps 
of paper would one day set in motion enormous rail- 
way trains. It will perhaps always be beyond our 
power to totally dissociate the atom, because the diffi- 
culties must increase as dissociation advances, but it 
would suffice if we could succeed in easily dissociat- 
ing a small part of it. Whether the gramme of 
dissociated matter that we have supposed be taken 
from a ton of matter or even more, matters nothing. 
The result would always be the same from the point 
of view of the energy produced. The researches 
which I have essayed on these lines, and which will 
be set forth here, show that it is possible to largely 
hasten the dissociation of various substances. 


The methods of dissociation are, as we shall see, 
numerous. The most simple is the action of light. 
It has further the advantage of costing nothing. In 
so fresh a field, with a new world opening out before 
us, none of our old theories should stop those who 
seek. " The secret of all who make discoveries," says 
Liebig, "is that they look upon nothing as impossible." 
The results that could be obtained in this order of 
researches are truly immense. The power to dissociate 
matter freely would place at our disposal an infinite 
source of energy, and would render unnecessary the 
extraction of that coal whereof the provision is 
rapidly becoming exhausted. The scholar who dis- 
covers the way to liberate economically the forces 
which matter contains will almost instantaneously 
change the face of the world. If an unlimited supply 
of energy were gratuitously placed at the disposal of 
man he would no longer have to procure it at the 
cost of arduous labour. The poor would then be on 
a level with the rich, and there would be an end to 
all social questions. 



Modern science formerly established a complete 
separation between matter and energy. The classic 
ideas on this scission will be found very plainly stated 
in the following passage of a recent work by Professor 
Janet : — 

"The world we live in is, in reality, a double world; or, rather, 
it is composed of two distinct worlds : one the world of matter, 
the other the world of energy. Copper, iron, and coal are forms 
of matter, mechanical labour and heat are forms of energy. 
These two worlds are each ruled by one and the same law. 
Matter can neither be created nor destroyed. Energy can 
neither be created nor destroyed. 

"Matter and energy can assume various forms without 
matter ever transforming itself into energy or energy into 
matter. . . . We can no more conceive energy without matter 
than we can conceive matter without energy." ^ 

Never, in fact, as says M. Janet, has it been 
possible till now to transform matter into energy; or, 
to be more precise, matter has never appeared to 
manifest any energy save that which had first been 
supplied to it. Incapable of creating energy, it could 
only give it back. The fundamental principles of 
thermodynamics taught that a material system 
isolated from all external action cannot spontaneously 
generate energy. 

' Janet, Lemons d^iUctricitiy 2nd edition, pp. 2 and 5. 



All previous scientific observations seemed to con- 
firm this notion that no substance is able to produce 
energy without having first obtained it from outside. 
Matter may serve as a support to electricity, as in the 
case of a condenser; it may radiate heat as in the case 
of a mass of metal previously heated; it may manifest 
forces produced by simple changes of equilibrium as 
in the case of chemical transformations; but in all 
these circumstances the energy disengaged is but the 
restitution in quantity exactly equal to that first com- 
municated to the portion of matter or employed in 
producing the combination. In all the cases just 
mentioned, as in all others of the same order, 
matter does no more than give back the energy 
which had firsit been given to it in some shape or 
other. It has created nothing, nothing has gone 
forth from itself. 

The impossibility of transforming matter into 
energy seemed therefore evident, and it was rightly 
invoked in the works which have become classic 
to establish a sharp separation between the world 
of matter and the world of energy. For this 
separation to disappear, it was necessary to 
succeed in transforming matter into energy without 
external addition. Now, it is exactly this spon- 
taneous transformation of matter into energy 
which is the result of all the experiments 
on the dissociation of matter set forth in this 
work. We shall see from them that matter can 
vanish without return, leaving behind it only 
the energy produced by its dissociation. The spon- 
taneous production of energy thus established, a 
production so contrary to the scientific ideas of the 
present time, appeared at first entirely inexplicable 


to physicists busied in seeking outside matter and 
failing to find it, the origin of the energy manifested. 
We have shown that the explanation becomes very 
simple so soon as one consents to recognize that 
matter contains a reservoir of energy which it can 
lose in part, either spontaneously or by the effect 
of slight influences. 

These slight influences act somewhat like a spark 
on a quantity of gunpowder — that is to say, by 
liberating energies far beyond those of the spark. 
Strictly it might be urged, doubtless, that in that 
case it is not matter which transforms itself into 
energy, but simply an intra-atomic energy which is 
expended; but as this matter cannot be generated 
without matter vanishing without return, we have 
a right to say that things happen exactly as if matter 
were transformed into energy. 

Such a transformation becomes, moreover, very 
comprehensible so soon as one is thoroughly pene- 
trated with the idea that matter is simply that form 
of energy endowed with stability which we have 
called intra-atomic energy. It results from this that 
when we say that matter is transformed into energy, 
it simply signifies that intra-atomic energy has 
changed its aspect to assume those divers forms 
to which we give the names of light, electricity, etc. 
And if, as we have shown above, a very small 
quantity of matter can produce, in the course of dis- 
sociation, a large amount of energy, it is because one 
of the most characteristic properties of the intra- 
atomic forces is their condensation, in immense 
quantities, within an extremely circumscribed space. 
For an analogous reason a gas compressed to a very 
high degree in a very small reservoir can give a 


considerable volume of gas when the tap is opened 
which before prevented its escape. 

The preceding notions were quite new when I 
formulated them for the first time. Several physi- 
cists are now arriving at them by different ways, 
but they do not reach them without serious 
difficulties, because some of these new notions 
are extremely hard to reconcile with certain classic 
principles. Many scholars have as much trouble 
in admitting them as they experienced fifty years 
ago in acknowledging as exact the principle of the 
conservatism of energy. Nothing is more difficult 
than to rid oneself of the inherited ideas which 
unconsciously direct our thoughts. 

These difficulties may be appreciated by reading a 
recent communication from one of the most eminent 
of living physicists, Lord Kelvin, at a meeting of the 
British Association, regarding the heat spontaneously 
given out by radium during its dissociation. Yet this 
emission is no more surprising than the continuous 
emission of particles having a speed of the same 
order as that of light, which can be obtained not 
only from radium, but from any substance whatever. 
It is utterly impossible," writes Lord Kelvin, 

that the heat produced can proceed from the stored 
energy of radium. It therefore seems to me abso- 
lutely certain that if the emission of heat continues 
at the same rate, this heat must be supplied from 

And Lord Kelvin falls back upon the common-place 

^ Philosophical Magazine^ February 1904, p. 122. Lord Kelvin, 
however, withdrew this at the Cambridge Meeting of the British 
Association (1904), and admitted that the whole energy of radio-active 
bodies must be self-contained.— F. L. 



hypothesis formed at the outset on the origin of the 
energy of radio-active bodies, which were attributable, 
as it was thought, to certain mysterious forces from 
the ambient medium. This supposition had no ex- 
perimental support. It was simply the theoretical 
consequence of the idea that matter, being entirely 
unable to create energy, could only give back what 
had been supplied to it. The fundamental principles 
of thermodynamics which Lord Kelvin has helped so 
much to found, tell us, in fact, that a material system 
isolated from all external action cannot spontaneously 
generate energy. But experiment has ever been 
superior to principles, and when once it has spoken, 
those scientific laws which appeared to be the most 
stable are condemned to rejoin in oblivion, the used- 
up, out-worn dogmas and doctrines past service. 

Other and bolder physicists, like Rutherford, after 
having admitted the principles of intra-atomic energy, 
remain in doubt. This is what the latter writes in a 
paper later than his book on radio-activity :— 

" It would be desirable to see appear some kind of chemical 
theory to explain the facts, and to enable us to know whether 
the energy is borrowed from the atom itself or from external 

Many physicists then, like Lord Kelvin, still keep 
to the old principles : that is why the phenomena of 
radio-activity, especially the spontaneous emission of 
particles animated with great speed and the rise in 
temperature during radio-activity, seem to them 
utterly unexplicable, and constitute a scientific 
enigma, as M. Mascart has recently said. The 
enigma, however, is very simple with the explanation 
I have given. 

^ Archives des Sciences physiques de Geneve ^ 1905, p. 53. 


One could not hope, moreover, that ideas so 
opposed to classic dogmas as intra-atomic energy 
and the transforming of matter into energy should 
spread very rapidly. It is even contrary to the usual 
evolution of scientific ideas that they, should be 
already widely spread, and should have produced all 
the discussions of which a summary will be found in 
the chapter devoted to the examination of objections. 
One can only explain this relative success by re- 
membering that faith in certain scientific principles 
had already been greatly shaken by such unforeseen 
discoveries as those of the X rays and of radium. 

The fact is that the scientific ideas which rule the 
minds of scholars at various epochs have all the 
solidity of religious dogmas. Very slow to be estab- 
lished, they are very slow likewise to disappear. 
New scientific truths have, assuredly, experience and 
reason as a basis, but they are only propagated by 
prestige — that is, when they are enunciated by scholars 
whose official position gives them prestige in the eyes 
of the scientific public. Now, it is this very category 
of scholars which not only does not enunciate them, 
but employs its authority to combat them. Truths 
of such capital importance as Ohm's law, which 
governs the whole of electricity, and the law of the 
conservation of energy which governs all physics, 
were received, on their first appearance, with in- 
difference or contempt, and remained without effect 
until the day when they were enunciated anew by 
scholars endowed with influence. 

It is only by studying the history of sciences, so 
little pursued at the present date, that one succeeds 
in understanding the genesis of beliefs and the laws 
governing their diffusion. I have just alluded to two 


discoveries which were among the most important of 
the past century, and which are summarized in two 
laws, of which one can say that they ought to have 
appealed to all minds by their marvellous simplicity 
and their imposing grandeur. Not only did they 
strike no one, but the most eminent scholars of the 
epoch did not concern themselves about them except 
to try to cover them with ridicule.^ 

That the simple enunciation of such doctrines 
should have appealed to no one shows with what 
difficulty a new idea is accepted when it does not fit 
in with former dogmas. Prestige, I repeat, and to a 
very slight extent experience are alone the ordinary 
foundation of our convictions — scientific and other- 
wise. Experiments — even those most convincing in 

^ When Ohm discovered the law which will immortalize his name, 
and on which the whole science of electricity rests, he published it in a 
book filled with experiments so simple and so conclusive that they 
might have been understood by any pupil in an elementary school. Not 
only did he fail to convince any one, but the most influential scholars 
of his time treated him in such a way that he lost the berth he occupied, 
and, to avoid dying of starvation, was only too glad to take a situation 
in a college at i-,200 francs per annum, where he remained for six 
years. Justice was only reiidered to him at the close of his life. 
Robert Mayer, less fortunate, did not even obtain this tardy satisfaction. 
When he discovered the most important of modern scientific laws, that 
of the conservation of energy, he had great difficulty in finding a review 
which would consent to publish his memoir, but no scholar bestowed 
the least attention upon it; any more, in fact, than on his subsequent 
publications, among them the one on the mechanical equivalent of heat, 
published in 1850. After attempting suicide, Mayer went out of his 
mind, and remained for a long time unknown, to such a degree that 
when Helmholtz re-made the same discovery, he was not aware that he 
had been forestalled. Helmholtz himself did not meet with any greater 
encouragement at the outset, and the most important of the scientific 
journals of that epoch, the Annales de Po^^endorff, declined to insert 
his celebrated memoir, "The Conservation of Energy," regarding it as 
a fanciful speculation unworthy the attention of serious readers. 


appearance — have never constituted an immediately 
demonstrable foundation when they clashed with 
long since accepted ideas. Galileo learned this to his 
cost, when, having brought together all the philo- 
sophers of the celebrated University of Pisa, he 
thought to prove to them by experiment that, 
contrary to the then accepted ideas, bodies of 
different weights fell with the same velocity. 
Galileo's demonstration was asisuredly very con- 
clusive, since by letting fall at the same moment 
from the top of a tower a small leaden ball and a 
cannon-shot of the same metal, he showed that both 
bodies reached the ground together. The professors 
contented themselves with appealing to the authority 
of Aristotle, and in nowise modified their opinions. 

Many years have passed away since that time, but 
the degree of receptivity of minds for new things has 
not sensibly increased. 



§ I. The Origin of Molecular Forces, 

Although matter was formerly considered inert, 
and only capable of preserving and restoring the 
energy which had first been given to it, yet it was 
necessarily established that there existed within it 
forces sometimes considerable, such as cohesion, 
affinity, osmotic attractions and repulsions, which 
were seemingly independent of all external agents. 
Other forces, such as radiant heat and electricity, 
which also issued from matter, might be considered 
simple restitutions of an energy borrowed from 

But if the cohesion which makes a rigid block out 
of the dust of atoms of which bodies are formed, or 
if that affinity which draws apart or dashes certain 
elements one upon the other and creates chemical 
combinations, or if the osmotic attractions and re- 
pulsions which hold in dependency the most im- 
portant phenomena of life, are visibly forces inherent 
to matter itself, it was altogether impossible with the 
old ideas to determine their source. The origin of 
these forces ceases to be mysterious when it is known 

that matter is a colossal reservoir of energy. Ob- 



servation having long ago shown that any form of 
energy whatever lends itself to a large number of 
transformations, we easily conceive how, from intra- 
atomic energy may be derived all the molecular forces : 
cohesion, affinity, etc., hitherto so inexplicable. We 
are far from being acquainted with their character, 
but at least we see the source from which they 

Outside the forces plainly inherent to matter that 
we have just enumerated, there are two, electricity 
and solar heat, the origin of which has always re- 
mained unknown, and which also, as we shall see, 
find an easy explanation by the theory of intra- 
atomic energy. 

§ 2. The Origin of Electricity. 

When we approach the detailed study of the facts 
on which are based the theories set forth in this w^ork, 
we shall find that electricity is one of the most con- 
stant manifestations of the dissociation of matter. 
Matter being nothing else than intra-atomic energy 
itself, it may be said that to dissociate matter is 
simply to liberate a little intra-atomic energy and 
to oblige it to take another form. Electricity is 
precisely one of these forms. 

For a certain number of years the r6le of electricity 
has constantly grown in iriiportance. It is at the base 
of all- chemical reactions, which are more and more 
considered as electrical reactions. It appears now as 
a universal force, and the tendency is to connect all 
other forces with it. That a force of which the 
manifestations have this importance and univers- 
ality should have been unknown for thousands of 
years constitutes one of the most striking facts in 


the history of science, and is one of those facts we 
must always bear in mind to understand how we 
may be surrounded with very powerful forces without 
perceiving them. 

For centuries all that was known about electricity 
could be reduced to this: that certain resinous sub- 
stances when rubbed attract light bodies. But might 
not other bodies enjoy the same property? By 
extending the friction to larger surfaces might not 
more intense effects still be produced ? This no one 
thought of inquiring. Ages succeeded each other 
before there arose a mind penetrating enough to ask 
itself such questions, and inquisitive enough to verify 
by experiment whether a body with a large surface 
when rubbed would not exercise an action superior 
in energy to that produced by a small fragment of 
the same body. From this verification which now 
seems so simple, but which took so many years to 
accomplish, we saw emerge the frictional electric 
machine of our laboratories and the phenomena it 
produces. The most striking of these were the 
apparition of sparks and violent discharges which 
revealed to an astonished world a new force and 
put into the hands of man a power of which he 
thought the gods alone possessed the secret. 

Electricity was then only produced very laboriously 
and was considered a very exceptional phenomenon. 
Now we find it everywhere and know that the simple 
contact of two heterogeneous bodies suffices to gene- 
rate it. The difficulty now is not how to produce 
electricity, but how not to give it birth during the 
production of any phenomenon whatever. The fall- 
ing of a drop of water, the heating of a gaseous mass 
by the sun, the raising of the temperature of a twisted 


wire, and a reaction capable of modifying the nature 
of a body, are all sources of electricity. 

But if all chemical reactions are electrical reac- 
tions, as is now said to be the case, if the sun cannot 
change the temperature of a body without disengag- 
ing electricity, if a drop of water cannot fall without 
producing it, it is evident that its r61e in the life of 
all beings must be preponderant. This, in fact, is 
what we are beginning to admit. Not a single 
change takes place in the cells of the body, no vital 
reaction is effected in the tissues, without the inter- 
vention of electricity. M. Berthelot has recently 
shown the important r61e of the electric tensions 
to which plants are constantly subjected. The varia- 
tions in the electric potential of the atmosphere 
are enormous, since they may oscillate between 600 
and 800 volts in fine weather, and rise to 15,000 volts 
at the least fall of rain. This potential increases 
at the rate of from 20 to 30 volts per mfetre in 
height in fine and from 400 to 500 volts in rainy 
weather for the same elevation. " These figures," he 
says, "give an idea of the potential which exists 
either between the upper point of a rod of which the 
other extremity is earthed, or between the top of a 
plant or a tree, and the layer of air in which that 
point or that top is bathed." The same scholar has 
proved that the efHuves generated by these differences 
of tension can provoke numerous chemical reactions: 
the fixation of nitrogen on hydrates of carbon, the 
dissociation of carbonic acid into carbonic oxide and 
oxygen, etc. 

After having established the phenomenon of the 
general dissociation of matter, I asked myself if the 
universal electricity, the origin of which remained 


unexplained, was not precisely the consequence of 
the universal dissociation of matter. My experi- 
ments fully verified this hypothesis, and they proved 
that electricity is one of the most important forms 
of intra-atomic energy liberated by the dematerializa- 
tion of matter. I was led to this conclusion after 
having satisfied myself that the products which 
escape from a body electrified at sufficient tension 
are entirely identical with those given out by radio- 
active substances on the road to dissociation. The 
various methods employed to obtain electricity, 
notably friction, only hasten the dissociation of 
matter. I shall refer, for the details of this demon- 
stration, to the chapter treating of the subject,^ con- 
fining myself at present to pointing out summarily 
the different generalizations which flow from the 
doctrine of intra-atomic energy. It is not electricity 
alone, but also solar heat, which, as we shall see, 
may be considered one of its manifestations. 

§ 3. Origin of Solar Heat. 

As we have fathomed the study of the dissociation 
of matter, so has the importance of this phenomenon 
proportionately increased. After recognizing that 
electricity may be considered one of the mani- 
festations of the dissociation of matter, I asked 
myself whether this dissociation and its result, the 
liberation of intra-atomic energy, were not also the 
cause, till now so unknown, of the maintenance 
of solar heat. The various hypotheses hitherto in- 
voked to explain the maintenance of this heat — 
the supposed fall of meteorites on the sun, for 
example — having all seemed extremely inadequate, 

^ Pp. 198 e/ seq, infra. 


it was necessary to seek others. Given the enor- 
mous quantity of energy accumulated within the 
atoms, it would be enough, if their dissociation were 
more rapid than it is on the cooled globes, to furnish 
the amount of heat necfessary to keep up the in- 
candescence of the stars. And there would be no 
need to presume, as was done when radium was 
supposed to be the only body capable of producing 
heat while dissociating, the unlikely presence of that 
substance in the sun, since the atoms of all bodies 
contain an immense store of energy. 

To maintain that stars such as the sun can keep 
up their own temperature by the helat resulting from 
the dissociation of their component atoms, seems 
much like saying that a heated body is capable 
of maintaining its temperature without any contribu- 
tion from outside. Now, it is well known that an 
incandescent body — a heated block of metal, for 
instance — when left to itself rapidly cools by radia- 
tion, though it be the seat of considerable atomic 
dissociation. But it cools, in fact, simply because 
the rise in temperature produced by the dissociation 
of its atoms during incandescence is far too slight 
to compensate for its loss of heat by radiation. The 
substances which, like radium, most rapidly dis- 
sociate, can hardly maintain their temperature at 
more than 3° to 4°C. above that of the ambient 
medium. Suppose, however, that the dissociation of 
any substance whatever were only one thousand 
times more rapid than that of radium, then the 
quantity of energy emitted would more than sufJfice 
to keep it in a state of incandescence. 

The whole question therefore is whether, at the 
origin of things^-that is to say, at the epoch when 



atoms were formed by condensations of an unknown 
nature, they did not possess such a quantity of energy 
that they have been able ever since to maintain the 
stars in a state of incandescence, thanks to their slow 
dissociation. This supposition is supported by the 
various calculations I have given as to the immense 
amount of energy contained within the atoms. The 
figures given are considerable, and yet J. J. Thomson, 
who has recently taken up the question anew, arrives 
at the conclusion that the energy now concentrated 
within the atoms is but an insignificant portion of 
that which they formerly contained and lost by 
radiation. Independently and at an earlier date, 
Professor Filippo R6 arrived at the same conclusion. 

If, therefore, atoms formerly contained a quantity 
of energy far exceeding the still formidable amount 
they now possess, they may, by dissociation, have 
expended during long accumulations of ages a part 
of the gigantic reserve of forces piled up within 
them at the beginning of things. They may have 
been able, and consequently may still be able, to 
maintain at a very high temperature stars like the 
sun and the heavenly bodies. In the course of time, 
however, the store of intra-atomic energy within 
the atoms of certain stars has at length been reduced, 
and their dissociation has become slower and slower. 
Finally, they have acquired an increasing stability, 
have dissociated very slowly, and have become such 
as one observes them to-day in the shape of cooled 
stars like the earth and other planets. 

If the theories formulated in this chapter be 
correct, the intra-atomic energy manifested during 
the dematerialization of matter constitutes the funda- 
mental element whence most other forces are derived. 


So that it is not only electricity which is one of its 
manifestations, but also solar heat, that primary 
source of life and of the majority of the forces at our 
disposal. Its study, which reveals to us matter in a 
totally new aspect, already permits us to throw un- 
foreseen light on the higher mechanics of our 



The criticisms called forth by my researches on 
intra-atomic energy prove that they have interested 
many scholars. As a new theory can only be solidly 
established by discussion, I thank them for their 
objections, and shall endeavour to answer them. 

The most important has been raised by several 
members of the Acad6mie des Sciences. This is 
what M. Henri Poincar6, one of the most eminent, 
wrote to me after the publication of my researches: — 

"I have read your memoir with the greatest interest. It 
raises a number of disturbing questions. One point to which I 
should like to call your attention is the opposition between your 
conception of the origin of solar heat and that of Helmholtz and 
Lord Kelvin. 

" When the nebula condenses into a sun its original potential 
energy is transformed into heat subsequently dissipated by 

" When the sub-atoms unite to form an atom this condensa- 
tion stores up energy in a potential form, and it is when the 
atom disaggregates that this energy reappears in the form of 
heat (disengagement of heat by radium). 

"Thus the reaction, * nebula to sun,* is exothermic. The 
reaction 'isolated sub-atoms to atoms' is endothermic, but if 
this ' combination ' is endothermic how comes it to be so extra- 
ordinarily stable ? " 

Another member of the Acad^mie des Sciences, 




M. Paul Painlev^, formulates the same objection, as 
follows: — 

" Thermodynamics teaches us the modifications which must 
be introduced into the celebrated principle of maximum work; 
we know that in a chemical combination stability and exother- 
mism are not strictly synonymous. None the less there 
remains the possibility that a * combination ' at the same time 
extraordinarily stable and extraordinarily endothermic is some- 
thing contrary, not indeed to the principle of the conservation 
of energy, but to the whole body of facts which up to recent 
times have been scientifically established." 1 

M. Naquet, late Professor of Chemistry at the 
Faculty de M^decine of Paris, who was unacquainted 
with M, Poincar^'s conclusions, expressed the same 

"There is one point, however, which I find embarrassing, 
especially if I adopt the most seductive of all hypotheses, that of 

Gustave Le Bon If the atoms disengage heat in the process 

of self-destruction they are endothermic, and, by analogy, should 
be excessively unstable. Now, on the contrary, they are the 
most stable things in the universe. 

" Here is a troublesome contradiction. We should not, how- 
ever, attach to this difficulty more importance than it possesses. 
Every time great systems have arisen difficulties of this kind 
have occurred. The authors of such systems have paid no 
attention to them. If Newton and his successors had allowed 
the perturbations they observed to stop them, the law of 
universal gravitation would never have been formulated." ^ 

The objection of MM. Henri Poincar^, Painlev6, 
and Naquet is evidently sound. It would be irre- 
futable were it applied to ordinary chemical com- 
pounds, but the laws applicable to the chemical 
equilibria of molecules do not appear to apply at all 
to intra-atomic equilibria. The atom alone possesses 

^ Revue Scientifique^ 27th January 1906, 
* Revue d^Iialie^ March and April 1904. 


these two contradictory properties, of being at 
orice very stable and very instable. It is very stable, 
since chemical reactions leave it sufficiently un- 
touched for our balances to find it always the same 
weight. It is very instable, since such slight causes 
as a ray of the sun, or the sinallest rise in tempera- 
ture suffice to begin its dissociation. This dissocia- 
tion is, no doubt, slight — in relation to the enormous 
quantity of energy accumulated within the atom, and 
it no more changes its mass than a shovelful of 
earth withdrawn from a mountain appreciably 
changes the weight of the latter. Yet the change 
is certain. We, therefore, have to do with special 
phenomena to which none of the customary laws 
of ordinary chemistry seem to apply. To put in 
evidence the special laws which regulate these new 
facts cannot be the work of a day. To interpret a 
fact is sometimes more difficult than to discover it. 

M. Armand Gautier, Member of the Institut and 
Professor of Chemistry at the Faculty de M^decine 
of Paris, has also taken up the question of intra- 
atomic energy in an article published^ by him on the 
subject of my researches. He recognizes that it is 
in the form of gyratory movements that intra- 
atomic energy may exist. I have not wished to enter 
into too many details on this point here, because it 
is evidently only hypothetical, and have confined 
myself to comparing the atom to a solar system, a 
comparison at which several physicists have arrived 
by different roads. Without such movements of 
gyration it would be impossible to conceive a con- 
densation of energy within the atom. With these 
movements it becomes easy to explain. Find the 

* Revue Scientijique^ February 1904, p. 213. 


means, as I have pointed out above, to give to a 
body of any size whatever, were it even less than 
that of a pin's head, a sufJficient speed of rotation, 
and you will communicate to it as considerable a 
provision of energy as you can desire. This is the 
precise condition which is realized by particles of 
atoms during their dissociation. 

M. Despaux, an engineer, on the contrary, entirely 
rejects the existence of intra-atomic energy. Here 
are his reasons: — 

" It is the dissociation of matter which, according to Gustave 
Le Bon, is the (5ause of the enormous energy manifested in radio- 

*'This view is quite a new one, and revolutionary in the 
highest degree. Science admifs the indestructibility of matter, 
and it is the fundamental dogma of chemistry ; it admits the 
conservatism of energy, and has made it the basis of mechanics. 
Here are two conquests one must then abandon. Matter trans- 
forms itself into energy and conversely. 

"This conception is assuredly seductive and in the highest 
degree philosophical. But this transformation, if it takes place, 
only does so by a slow process of evolution. During any given 
epoch, all the phenomena studied by science lead to the 
belief that the quantity of matter and the quantity of energy 
are invariable. 

''Another objection arises, and a formidable one: Is it 
possible that so trifling an amount of matter carries in its loins 
so considerable a quantity of energy ? Our reason refuses to 
believe it."* 

Let us leave on one side the principle of the conser- 
vation of energy, which cannot evidently be discussed 
in a few lines, and remains, moreover, partly intact if it 
be recognized that the atom, by dissociation, simply 
gives back the energy it has stored up, at the be- 

* Revue Scientifique, 2nd January 1904. 


ginning of the ages, during its formation. The objec- 
tions of M. Despaux reduce themselves, then, to this: 
reason refuses to admit that matter can conceal so 
considerable a quantity of energy. I simply reply 
that it is a question of an experimental fact, amply 
pi'oved by the emission of particles endowed with 
a speed of the order of that of light, and by the large 
quantity of calories given forth by radium. The 
number of things that reason at first refused to 
recognize and yet had in the end to admit is con- 

However, I am willing to acknowledge that this 
conception of the atom as an enormous source of 
energy, and of such energy that one gramme of 
any substance whatever contains the equivalent of 
several thousand million kilogramm^tres, is too much 
opposed to received ideas to penetrate rapidly into 
men's minds. But this is solely due to the fact 
that the intellectual moulds fashioned by education 
do not change easily. M. A. Duclaud has put this 
excellently in an article on the same subject, of 
which this is an extract : — ^ 

"The consequences of the experiments of Gustave Le 
Bon, which appear to rebel against the scientific dogmas 
of the conservation of energy and of the indestructibility of 
matter, have excited numerous objections. It follows that 
men's minds hardly lend themselves to the admission that 
matter can emit spontaneously (that is, by itself and without 
any external aid) more or less considerable quantities of energy. 
This arises from that very old conception of the 'duality of 
force and matter' which, by bringing us to consider them 
two distinct terms, compels us to regard matter as by itself 
inert. . . . One Can regard matter as non-inert, as being *a 
colossal reservoir of forces that it is able to expend without 

^ Revue Scientifique^ 2nd April 1904. 


borrowing anything from outside/ without on that account 
attacking the principle of the conservation of energy. 

" But the attack which aims at the indestructibility of matter 
seems more serious. Still, after due reflection, I think we 
should only see in this a question of words. 

"As a matter of fact, Gustave Le Bon presents to us four 
successive stages of matter . . . while showing that everything 
returns to ether, he allows also that everything proceeds from it. 
* Worlds are bom therein, and go there to die,' he tells us. 

'* The ponderable issues from the ether, and returns to it under 
manifold influences. That is to say, the ether is a reservoir, at 
once the receptacle and the pourer-forth of matter* Now, unless 
we admit that there is a loss on the part of the ether, a leakage 
from the reservoir in the course of this perpetual exchange between 
the ponderable and the imponderable, it is impossible to con* 
elude that there is a disappearance of any quantity of matter. 
And tiie idea of a loss on the part of the ether is inadmissible, 
for it leads to the absurd conclusion that that which is lost must 
diffuse itself outside space, since, by the hypothesis, the ether 
fills all space.'' 

M. Laisant, examiner at the Ecole Polytechnique, 
expresses similar views in a paper on these re- 
searches : — ' 

"A small quantity of matter, for instance, a gramme, contains, 
according to Gustave Le Bon's theory, an amount of energy 
which, if it were liberated, would represent thousands of millions 
of kilogram metres. What becomes, on this conception, of the 
immaterial ether in which matter is about to lose itself? It is a 
sort of final nirvana^ in the words of the author, an infinite and 
motionless nothingness, receiving everything and giving back 
nothing. In the stead of this eternal cemetery of the atoms, I 
Strive to see in the ether rather the perpetual laboratory of 
nature. I would even go so far as to say that it is to the atom 
what, in biology, protoplasm is to the cell. Everything goes to 
and comes forth from it. It is a form of matter, at once its 
original and the final form."^ 

I have no reason to contradict the two authors last 

^ " L'Enseignement mathematique," 15th January 1906. 


quoted onihe fate of matter when it has disappeared. 
A.11 I wanted to establish, in fact, was that ponderable 
matter vanishes without return by liberating the 
enormous forces it contains. Once returned to the 
ether, matter has irrevocably ceased to exist, so 
far as we are concerned. Its individuality has com- 
pletely disappeared. It has become something un- 
recognizable and eliminated from the sphere of the 
world accessible to our senses. There is assuredly a 
much greater distance between matter and ether 
than there is between carbon or nitrogen and the 
living beings formed from their combinations. Car- 
bon and nitrogen can, in fact, indefinitely recom- 
mence their cycle by falling again under the laws of 
life; while matter returned to the ether can no 
more become matter again — or at least can only 
do so by colossal accumulations of energy which 
demand long successions of ages for their forma- 
tion, and which we could not produce without 
the power attributed in the Book of Genesis to the 

It is, generally, mathematicians and engineers who 
receive my ideas with most favour. But in his 
inaugural discourse as President of VAssociation 
Frangaise pour VAvancement des Sciences, M. Laisant, 
quoted above, produced one of my most im- 
portant conclusions, and showed all the bearing 
it may have in the future. It is especially abroad, 
however, that these ideas have found most echo. 
Professor Filippo R6 detailed them at length in the 
Rivista di Fisiea, and in a technical review ex- 
clusively designed for engineers.^ 

^ Bulletin de C Association des Inginieurs de VEcole polytechnique 
de Bruxelies, Deccml)er 1903. 


Professor Somerhausen has devoted to them a 
memoir from which I will give a few extracts be- 
cause they show that in many thinking minds the 
fundamental principles of modern science have not 
inspired very unshakeable convictions. 

"A Revolution in Science, — This title is apt, for the facts and 
hypotheses of which we are about to treat tend to do nothing less 
than sap two principles we have admitted as the most un- 
shakeable foundations of the scientific edifice. . . . If one frees 
oneself from the tendency to arrange new facts in already 
known categories, one will have to admit that the remarkable 
facts we have examined cannot be explained by the known 
modes of energy, and they must necessarily be interpreted, with 
Gustave Le Bon, as the manifestation of an energy hitherto 

*' We have established, on the one hand, the new phenomenon 
of atomic dissociation, and, on the other, the production of 
considerable energy without any possible explanation by known 
means. It is evidently logical to connect the two facts, and 
attribute to the destruction of the atom the freeing of the new 
energy — of intra-atomic energy, 

'^ Gustave Le Bon supposes that the dissociated atom has 
acquired properties intermediate between matter and ether, and 
between the ponderable and the imponderable. But from the 
point of view of the effects, nearly everything takes place as if by 
a direct transformation from matter into energy. . . . We there- 
fore see matter here appearing as a direct source of energy, 
which vitiates all the applications of the principle of the conserva- 
tion of energy. And as we have had to admit the possibility of 
the destruction of matter, we have to admit the possibility of the 
creation of energy. We now begin to discern the possibility, by 
combining the terms matter and energy, of arriving at a definitive 
equation which may be looked upon as the highest symbol of 
the phenomena of the universe. 

"It will certainly be one of the grandest conquests of science 
if we succeed, after having passed the stage of the unity of 
matter, in joining the domain of matter with that of energy, and 
thus clear away the last discontinuity in the structure of .the 


Among the objections which I ought to mention 
there is one which must certainly have occurred to the 
minds of many. It was formulated by Professor Pio, 
in one of the four articles he published under the 
title " Intra- Atomic Energy," in an English scien- 
tific review.^ I will discuss it after reproducing a 
few passages from these articles. 

"All the new phenomena — cathode rays, emanations from 
radium, etc., have been explained by the doctrine of the disso- 
ciation of matter by Gustave Le Bon. . . . The phenomenon of 
the dissociation of matter discovered by the latter is as marvellous 
as it i6 astounding. It has not, however, excited • the same 
attention as the discovery of radium, because the close link 
which connects these two discoveries has not been perceived. 
. . . These experiments open a perspective to inventors which 
Surpasses all dreams. There is in Nature an immense source of 
force which we do not know. . . . Matter is no longer inert, but 
a prodigious store-house of energy. . . . The theory of intra* 
atomic energy leads to ah entirely new conception of natural 
forces. . . . Till now we have only known of forces acting on 
atoms from without: gravitation, heat, light, afHnity, etc. Now 
the atom appears as a generator of energy independent of all 
external force. All these phenomena will serve as a foundation 
for a new theory of energy." 

The objection of the author to which I have 
alluded is this: 

" How is it," he asks, " that particles . emitted 
under the influence of intra-atomic energy with an 
enormous speed do not render incandescent by the 
shock the bodies they strike, and where does the 
energy expended go to?" The answer is: if the 
particles are emitted in sufficient numbers, they may, 
in fact, render metals incandescent by the shock, as 
is observed on the anti-cathode of Crookes' tube. 

^ English Mechanic^ 2ist January, 4th March, 15th April, and 13th 
May 1904. 


With radium, and still more with ordinary substances 
infinitely less active, the energy is produced too 
slowly to generate such important effects. At the 
most, as is the case with radium, it may raise the 
temperature of the mass of the body by two or three 
degrees. Radium releases, according to the measure- 
ments of Curie, loo calorie-grammes per hour, and 
this quantity could only raise the ten^perature of loo 
grammes of water by one degree in an hour. It is 
evidently too slight to raise in any appreciable way 
the temperature of a metal, especially if one considers 
that this would cool by radiation nearly as fast as it 
was heated. 

Certainly it would be quite different if radium or 
any other substance were dissociated rapidly instead 
of requiring centuries for the purpose. The scholar 
who discovers the way to dissociate instantaneously 
one gramme of any metal — radium, lead, or silver — 
will not witness the results of his experiment. 
The explosion produced would be so formidable that 
his laboratory and all the neighbouring houses, with 
their inhabitants, would be instantaneously pul- 
verized. So complete a dissociation will probably 
never be attained, though M. de Heen attributes to 
explosions of this kind the sudden disappearance of 
certain stars. Yet there is hope that the partial 
dissociation of atoms may be rendered less slow. I 
assert this, not as the result of theory, but as of 
experiment, since, by the means set forth in the 
sequel, I have been able to render metals almost 
deprived of radio-activity, like tin, forty times more 
radio-active than an equal surface of uranium. 

The preceding discussions show that the doctrine 
of intra-atomic energy has attracted much morei 


notice than that of the universality of the dissocia- 
tion of matter. Yet the first-named was only the 
consequence of the second, and it was necessary 
to establish the facts before looking for the 

It is especially these consequences which have 
made an impression. One of our most important 
publications, the Annie Scientifique} has remarked 
this very clearly in a summary of which I give some 
extracts: — 

" M. Gustave Le Bon was the first, as we should not forget, to 
throw some light into this dark chaos, by showing that radio- 
activity is not peculiar to a few rare substances, such as uranium, 
radium, etc., but is a general property of matter, possessed in 
varying degrees by all bodies. 

*' . . . Such is, briefly and in its larger outlines, Gustave Le 
Bon's doctrine, which upsets all our traditional acquirements 
as to the conservation of energy and the indestructibility of 
matter. Radio-activity, a general and essential pi:operty of 
matter, should be the manifestation of a new mode of energy 
and of a force — the intra-atomic— hitherto unknown. 

*'We do not yet know how to liberate and master this incal- 
culable reserve of force, of which yesterday we did not even 
suspect the existence. But it is evident that when man shall 
have found the means to make himself its master, it will be 
the greatest revolution ever recorded in the annals of the genius 
of science, a revolution of which our puny brains can hardly 
grasp all the consequences and the extent." 

The philosophic consequences of these researches 
have not escaped several scholars. In an analysis of 
the first edition of this work published in the Revue 
Philosophique for November 1905, M. Sagaret, an 
engineer, has fully shown these consequences. Here 
are some extracts from his article: — 

* 47 th year, pp. 6, 88 and 89. 


" No scientific theory has responded nor can better respond 
to our yearning for unity than that of Dr. Gustave Le Bon. 
It sets up a unity than which it would be impossible to imagine 
anything more complete, and it focusses our knowledge on the 
following principle: one substance alone exists which moves and 
produces all things by its movements. This is not a new con- 
ception, it is true, for the philosopher, but it has remained 
hitherto a purely metaphysical speculation. To-day, thanks to 
Dr. Gustave Le Bon, it finds a starting-point in experiment 

" The scholar has till now stopped at the atopi without per- 
ceiving any link between it and the ether. The duality of the 
ponderable and the imponderable seemed irreducible. Now 
the theory of the dematerialization of matter comes to establish 
a link between them. 

" But it realizes scientific unity in yet another way by making 
general the law of evolution. This law, hitherto confined to the 
organic world, now extends to the whole universe. The atom, 
like the living being, is born, develops and dies, and Dr. 
Gustave Le Bon shows us that the chemical species evolves 
like the organic species." 





Science formerly divided the various phenomena 
of nature into two sharply separated classes, with 
no apparent break between them. These distinctions 
have existed throughout all branches of knowledge, 
and in physics as well as in biology. 

The discovery of the laws of evolution has caused the 
disappearance from the natural sciences of divisions 
which formerly seemed impassable gulfs, and, from 
the protoplasm of primitive beings up to man the 
chain is now almost uninterrupted. The missing links 
are every day re-forged and we get glimpses of how 
the change from the simplest to the most complicated 
beings has operated step by step throughout time. 

Physics has followed an analogous route, but has 
not yet arrived at unity. It has, however, rid itself 
of the fluids which formerly encumbered it; it has dis- 
covered the relations which exist between the different 
forces, and has recognized that they are but varied 
manifestations of one thing supposed to be inde* 



stmctible: to wit, energy. It has also established 
permanence throogfaoat the smes of phenomqia, and 
has shown the existence of the continiioiis wheie 
there formeriy appcsLted only the discontinuous. 
The law of the conserTati<Mi of energy is in reality 
only the simple verification of this continuity. 

There remain, howevo*, in physics two deep gaps 
to be filled before this continuity can be established 
everywhere. Phjrsics, in fatct, still maintains a wide 
separation exists between matter and energy, and 
another, not less considerable, between the world of 
the ponderable and that of the imponderable — that is 
to say, between matter and the ether. Matter is that 
which is weighed. Light, heat, electricity and all the 
phenomena produced in the bosom of the imponder- 
able ether, as they add nothing to the weight of 
bodies, are regarded as belonging to a very different 
world from that of matter. 

The scission of these two worlds seemed finally 
established. The most illustrious scholar of our 
times bad even come to consider the demonstration 
of this separation as one of the greatest discoveries 
of all ages. This is how M. Bertbelot expressed 
himself on the subject at the recent inauguration of 
the monument to Lavoisier : — 

" Lavoisier established, by most exact experiments, a capital 
and, until his time, unrecognized distinction between the ponder- 
able substances and the imponderable aj^encies, heat, light, and 
electricity. This fundamental distinction between ponderable 
matter and imponderable agencies is one of the greatest 
discoveries ever made; it is one of the bases of the present 
physical, chemical, and mechanical sciences.'' 

A fundamental base, in fact, and one which till now 
has appeared unshakeable. The phenomena due to 



the transformations of the imponderable ether, such 
as light, for instance, present no appreciable analogy 
with those of which matter is the seat. Matter may 
change its form, but, in all these changes, it preserves 
an invariable weight. Whatever be the modification 
to which the imponderable agencies submit it, they 
do not add to it and never cause any variation in its 

To thoroughly grasp modern scientific thought on 
this point, the above quotation must be considered 
in connection with that relating to the separation of 
matter and energy, reproduced in a previous chapter.^ 
They show that the science of the day is confronted 
not with one only, but with several very distinct 
dualities. They may be formulated in the following 
propositions : — ist. Matter is entirely distinct from 
energy and cannot of itself create energy ; 2nd. The 
imponderable ether is entirely distinct from ponder- 
able matter and has no kinship with it. The solidity 
of these two principles has hitherto seemed to defy 
the ages. We shall endeavour to show, on the 
contrary, that the new facts tend to utterly upset 

So far as regards the non-existence of the classic 
separation between matter and energy, we need not 
recur to it, since we have devoted a chapter ^ to de- 
monstrating that matter can be transformed into 
energy. It therefore only remains for us to inquire 
whether the distinction between matter and ether 
can equally disappear. A few scholars here and 
there had already remarked the jarring character of 
this last duality and how it rendered impossible the 

' Cf, M. Janet's remarks, p. 52 an(} BQok 11,, chap. ii. sufra, — F, Li 
' Sf e last not§, 


explanation of certain phenomena. Larmor has 
recently employed the manifold resources of mathe- 
matical analysis in the attempt to do away with what 
he calls " the irreconcilable duality of matter and 
ether." But if this duality is destined to vanish, ex- 
perience alone. can show that it ought to disappear. 
Now, the facts recently discovered, notably those 
relating to the universal dissociation of matter, are 
sufficiently numerous to allow of an attempt to con-* 
nect the two worlds till now so widely separated. 

At first sight, the task seems a heavy one. It is not 
easy, in fact, to see how a material substance, having 
weight, with well-defined outlines, such as a stone or 
a piece of lead, can be akin to things so mobile and 
so subtle as a sunbeam or an electric spark. But we 
know, from all the observations of modern science, 
that it is not by bringing together the extremities of a 
series that the intermediate forms can be reconstructed 
and the analogies hidden under their dissimilarities 
discovered. It is not by comparing the beings who 
were born at the dawn of life with the higher order of 
animals with which our globe was afterwards peopled 
that the links uniting them were discovered. By pro- 
ceeding in physics as we have done in biology, we shall 
see, on the contrary, that it is possible to bring nearer 
together things apparently so dissimilar as matter, 
electricity, and light. 

The facts which enable us to prove the existence 
of an intermediate world between matter and ether 
are in reality becoming more numerous every day; 
They have only needed synthetizing and interpreting. 
To say with reason that a certain substance can be 
considered as intermediate between matter and ether, 
it must possess characteristics allowing it to be at 


once compared to and differentiated from both these 
elements. It is because characteristics of this kind 
have been verified among the anthropoid apes that 
naturalists now consider them as forming a link 
between the inferior animals and man. The method 
which we shall apply will be that of the naturalists. 
We shall seek out the intermediate characteristics 
which allow us to say that a substance, while some- 
what resembling matter, is yet not matter, and while 
near to the ether, is yet not the ether. 

Several chapters of this work will be devoted to 
this demonstration, of which we can only at present 
indicate the results. We shall endeavour to show, 
while throughout taking experiment for our guide, 
that the products of the dematerialization of matter 
— that is to say, the emissions produced during its 
dissociation — are formed from substances of which 
the characteristics are intermediate between those of 
ether and those of matter. 

Of what do these substances consist ? Wherein have 
they lost the properties of material bodies ? For a 
number of years physicists have persisted in seeing 
in the emissions of radio-active bodies only frag- 
ments of matter more or less tenuous. Unable to rid 
themselves of the concept of material support, they 
have supposed that the particles emitted were merely 
atoms — charged with electricity, no doubt, but still, 
however, formed of matter. This opinion seemed 
confirmed by the fact that the radio-active emissions 
were most often accompanied by the projection of 
material particles. In Crookes' tube the emission 
of solid particles thrown off by the cathode is 
so considerable that it has been possible to cover 
with metal bodies exposed to their bombardment. 


This transport (entratnement) of matter is, how- 
ever, observed in most electrical phenomena, notably 
when electricity of a sufficiently high potential passes 
between two electrodes. The spectroscope, in fact, 
always reveals, in the light of the sparks, the char- 
acteristic lines of the metals of which these electrodes 
are composed. Yet another reason seemed to prove 
the material nature of these emissions. They could 
be deviated by a magnetic field, and were therefore 
charged with electricity. Now, as no one had yet 
seen the transport of electricity without material 
support, the existence of such a support was con- 
sidered evident. 

The sort of material dust which was thus supposed 
to constitute the emissions from the cathode and 
those from radio-active bodies presented singular char- 
acteristics for a material substance. Not only does it 
present the same properties whatever the body dis- 
sociated, but it has also lost all the characteristics of 
the matter which gives it birth. Lenard showed this 
clearly when he sought to verify one of his old 
hypotheses, according to which the efiluves generated 
by ultra-violet light striking on the surface of metals 
are composed of the dust torn from those metals. 
Taking sodium, a body very easily dissociated 
by light and the smallest traces of which in the 
air can be recognized by. the spectroscope, he 
found that the effluves thus emitted contained no 
trace of sodium. If, then, the emissions of dis- 
sociated substances are matter, it is matter which 
has none of the properties of the substances whence 
it comes. 

Facts of this nature have multiplied sufiiciently 
to prove that in the cathode radiation, as well as 


in radio-activity, matter transforms itself into some- 
thing which can no longer be ordinary matter, since 
none of its properties are preserved. It is this thing 
of which we are about to study the characteristics, 
and which we shall show belongs to the intermediate 
world between matter and the ether. 

So long as the existence of this intermediate world 
was ignored, science found itself confronted with 
facts that it could not classify. Thus it was, for 
example, that physicists were puzzled where to place 
the cathode rays which really form part of the inter- 
mediate substances between matter and the ether. 
This is why they placed them first in the world 
of matter and then in that of ether, notwith- 
standing that the two worlds were considered so 
different. Nor could they naturally class them 
otherwise. Since physics supposes that phenomena 
can only belong to one of these two worlds, what 
does not belong to the one necessarily belongs to the 
other. In reality, they belong to neither the one nor 
the other, but to that intermediate world between 
the ether and matter that we shall study in this 
work. It is peopled with a crowd of things entirely 
new, the acquaintance of which we are hardly be- 
ginning to make. 




The greater part of physical phenomena — light, 
heat, radiant electricity, etc., are considered to have 
their seat in the ether. Gravitation, whence are 
derived the mechanics of the world and the march 
of the stars, seems also to be one of its manifesta- 
tions. All the theoretical researches formulated on 
the constitution of atoms lead to the supposition that 
it forms the material from which they are made. 
Although the inmost nature of the ether is hardly 
suspected, its existence has forced itself upon us long 
since, and appears to many to be more assured than 
that of matter itself. Belief in its existence became 
necessary when the propagation of forces at a distance 
had to be explained. It appeared to be experiment- 
ally demonstrated when Fresnel proved that light is 
spread by undulations analogous to those produced 
by the falling of a stone into water. By the inter- 
ference of luminous rays he obtained darkness by the 
superposition of the prominent parts of one luminous 
wave upon the hollow parts of another. As the 
propagation of light is effected by means of un- 
dulations, these undulations are necessarily produced 
in something. This something is what is called the 

Its role has become of capital importance, and has 



not ceased to increase with the progress of physics. 
The majority of phenomena would be inexplicable 
without it. Without the ether there could be neither 
gravity, nor light, nor electricity, nor heat, nor any- 
thing, in a word, of which we have knowledge. 
The universe would be silent and dead, or would 
reveal itself in a form which we cannot even foresee. 
If one could construct a glass chamber from which 
the ether were to be entirely eliminated, heat and 
light could not pass through it. It would be abso- 
lutely dark, and probably gravitation would no 
longer act on the bodies within it. They would then 
have lost their weight. 

But so soon as one seeks to define the properties of 
the ether, enormous difficulties appear. No doubt 
they are due to the fact that as this immaterial 
element cannot be connected with any known thing, 
terms of comparison are entirely wanting for its 
definition. Before phenomena without analogy to 
those habitually observed, we are like a person born 
deaf with regard to music, or a blind man with 
regard to colours. No image can make them under- 
stand what is a sound or a colour. 

When books on physics state in a few lines that 
the ether is an imponderable medium filling the 
universe, the first idea coming into the mind is to 
represent it as a sort of gas so rarefied as to be im- 
ponderable by the means at our disposal. There is 
no difficulty in imagining such a gas. M. MuUer has 
calculated that if the matter of the sun and its 
surrounding planets were diffused through a space 
equal to that which divides the stars closest together, 
a cubic myriametre of this matter, in a gaseous state, 
would hardly weigh the thousandth part of a milli- 


gramme, and consequently could not be weighed in 
our balances. This finely-divided fluid, which perhaps 
represents the primitive condition of our nebula, 
would be a quadrillion times less dense than the 
vacuum of the thousandth part of an atmosphere in 
a Crookes' tube.^ 

Unfortunately the properties of the ether do not 
permit it to be in any way likened to a gas. Gases 
are very compressible and the ether cannot be so. If 
it were, in fact, it could not transmit, almost in- 
stantaneously, the vibrations of light. It is only in 
theoretically perfect fluids, or, better still, in solids, 
that distant analogies with the ether can be dis- 
covered, but then a substance with very singular 
qualities has to be imagined. It must possess a 
rigidity exceeding that of steel, or it could not 
transmit luminous vibrations at a velocity of 300,000 
kilomfetres per second. One of the most eminent of 
living physicists. Lord Kelvin, considers the ether 
to be "an elastic solid filling all space." But 
the elastic solid forming the ether must have very 
strange properties for a solid, which we never meet 
with in any other. Its extreme rigidity must be 
accompanied by an extraordinarily low density — that 
is to say, one small enough to prevent its retarding by 
its friction the movement of the stars through space. 
Hirn has shown that if the density of ether were but 
a million times less than that of the air, rarefied 
as it is, contained in a Crookes' tube, it would cause 
an alteration of half a second every hundred years in 

* Professor Mendel^eff in his Principles of Chemistry gives his reasons 
for thinking that the ether is a gas of the argon group, incapable of 
combination, with an atomic weight one-millionth of that of hydrogen 
and a velocity of 2,250 kilometres per second. (Eng. ed. 1905, vol. ii« 
p. 526.) — F. L. 


the mean motion of the moon. Such a medium, 
notwithstanding its reduced density, would, how- 
ever, very quickly expel the atmosphere from the 
earth. It has been calculated also that, had it the 
properties we attribute to gases, it would acquire, 
by its impact with the surface of stars deprived, like 
the moon, of their atmosphere, a temperature of 
38,000° C. Finally, one is thrown back on the idea 
that the ether is a solid without density or weight, 
however unintelligible this may seem. 

Other physicists have recently maintained that the 
density of the ether must, on the contrary, be very 
great. They found their notion on the electro- 
magnetic theory of matter which attributes the 
inertia of all matter to the ether. According to this 
theory, the mass of a body is nothing else than the 
mass of the surrounding ether, held and dragged along 
by the lines of force which encompass the electric 
particles of which atoms are supposed to be formed. 
All the inertia of bodies — that is to say, their mass, is 
due to the inertia of the ether. All kinetic energy is 
due to the movements of the ether imprisoned by the 
lines of force which unite it to the atoms. J. J. 
Thomson, who upholds this hypothesis,^ adds, "that 
it requires that the density of the ether should exceed 
that of all known bodies." Why, however, is not 
very clear. 

The magnitude of the forces which the ether is able 
to transmit likewise constitutes a phenomenon very 
difficult to interpret* An electro-magnet acts across 
space by the intermediary of the ether. Now, as 

1 "Electricity and Matter," Westminster, 1904; and "On the 
Dynamics of an Electrified Field,** Proceedings of the Cambridge Phiio- 
sophical Society y I903» P» 83* 



Lord Kelvin has remarked, it exercises on iron at a 
distance a force which may extend to no kilo- 
grammes per square centimetre. " How is it," this 
physicist writes, "that these prodigious forces are 
developed in the ether, an elastic solid, while 
ponderable bodies are yet free to move within this 
solid ? " We do not know and cannot say if we ever 
shall know. 

Hardly anything can be indicated concerning the 
constitution of the ether. Maxwell supposed it 
to be formed of little spheres animated by a very 
rapid rotatory movement, which each transmitted to 
its neighbour. Fresnel considered its elasticity con- 
stant, but its density variable. Other physicists 
believe, on the other hand, that its density is constant 
and its elasticity variable. For most it is not dis- 
turbed by the motions of the material systems which 
pass through it. Others, again, think that, on the 
contrary, it is carried along by them. 

It is, in any case, agreed that the ether is a sub- 
stance very different to matter, and is withdrawn 
from the laws of gravity. It has no weight, is 
immaterial in the usual acceptation of that word, 
and forms the world of the imponderable. Yet if the 
ether has no gravity it must have mass, since it offers 
resistance to movement. This mass is slight, since 
the speed of the propagation of light is very greats 
If there were no mass the propagation of light would 
probably be instantaneous. The question of thq 
imponderability of the ether, so long debated, now 
seems definitely settled. It has been taken up again 
recently by Lord Kelvin,^ and, by mathematical 

* ** On the Clustering of Gravitational Matter in any Part of th^ 
Universe," Philoiophical Magazine, January 1902. 



calculations which cannot be reproduced here, he 
arrives at the conclusion that the ether consists of a 
substance entirely outside the laws of gravitation — 
that is to say, imponderable. But he adds, " We 
have no reason to consider it as absolutely in- 
compressible, and we may admit that a sufficient 
pressure would condense it." 

It is probably from this condensation, effected at 
the beginning of the ages by a mechanism totally 
unknown to us, that are derived the atoms, con- 
sidered by several physicists— Larmor especially — 
as condensation nuclei in the ether, having the form 
of small vortices (or whirlpools) animated with an 
enormous speed of rotation. " The material mole- 
cule," writes this physicist, " is entirely formed of 
ether and of nothing else." ^ 

Such are the properties that the interpretation of 
the phenomena attributes to the ether. We must 
confine ourselves to stating, without being able to 
understand it, that we are living in an immaterial 
medium more rigid than steel, to which medium we 
can easily communicate, simply by burning any body 
whatever, movements of which the speed of propaga- 
tion is 300,000 times greater than that of a cannon- 
ball. The ether is an agent of which we catch 
glimpses everywhere around us, which we can cause 
to vibrate, to deviate, and which we can measure at 
will, without being able to isolate it. its inmost 
nature remains an irritating mystery. 

We may sum this up by saying that if we know 
very little about the ether, we must, however, 
consider it certain that the greater part of the 
phenomena in the universe are the consequences of 

1 Ether atid MatUn London, 1900. 


its manifestations. It is, no doubt, the first source 
and the ultimate end of things, the substratum of 
the worlds and of all beings moving on their surface. 
I will endeavour to show soon how the imponder- 
able ether can be connected with matter and thus 
grasp the link connecting the material with the 
immaterial. As a preparation for understanding 
their relations, we will first examine some of the 
equilibria it is possible to observe in the ether. We 
only know a small number of these, but those we are 
able to observe will permit us, by analogy, to foresee 
the nature of those unknown to us. 




The most important phenomena in nature: heat, 
light, electricity, etc., have, as we have just seen, 
their seat in the ether. They are generated by cer- 
tain perturbations of this immaterial fluid on leaving 
or returning to equilibrium. The iforces of the 
universe are only known to us, in reality, by dis- 
turbances of equilibrium. The state of equilibrium 
constitutes the limit beyond which we can no longer 
follow them. Light is only a change of the 
equilibrium of the ether, characterized by its 
vibrations; it ceases to exist so soon as the 
equilibrium is re-established. The electric spark 
of our laboratories, as also the lightning, are simple 
manifestations of the changes of the electric fluid 
leaving its equilibrium from one cause or another, and 
striving to return to it. So long as we knew not 
how to draw the electric fluid from its state of repose 
its existence was ignored. 

All the modifications of equilibrium produced in 
the ether are very instable and do not survive the 
cause which gave them birth. It is just this which 
differentiates them from material equilibria. The 
various forms of equilibrium observed in matter are 
generally very stable — that is, they survive the cause 
which generates them. The world of the ether 



is the world of mobile equilibria, while the world 
of matter is that of equilibria which can be fixed. 

To say that a thing is na longer in equilibrium is 
to state that it has undergone certain displacements. 
The known movements which determine the appear- 
ance of phenomena are not very numerous. They 
are principally attractions, repulsions, rotations, 
projections, vibrations and vortices, and of these 
different movements the best known are those which 
produce attractions and repulsions, as they are 
almost exclusively resorted to for the measurement 
of phenomena. The balance measures the attraction 
exercised on bodies by the earth, the galvanometer 
measures the attraction exercised on a magnet by 
an electric current, the thermometer, the attractions 
or repulsions of the molecules of a liquid submitted 
to the influence of heat. The osmotic equilibria 
which control most of the phenomena of life are 
revealed by the attractions and repulsions of the 
molecules in the bosom of liquids. The movements 
of various substances and the varieties of equilibrium 
resulting therefrom thus play a fundamental r61e in 
the production of phenomena. They constitute 
their essence, and form the only realities accessible 
to us. 

Until the last few years, only the regular vibratory 
movements of the ether which produce light were 
studied. It might, however, have been supposed 
that a fluid in which, as in a liquid, regular waves 
could be produced, was susceptible of other, move- 
ments. It is now recognized that the ether can be 
the seat of different movements such as projections, 
rotations, vortices, etc., and, among the forms of the 
movements in the ether lately studied, vortices 

- I 



appear, theoretically at least, to play a preponderant 
part. Larmor^ and other physicists consider that 
electrons, the supposed' elements of the electric 
fluid — and, according to some scholars, of material 
atoms — are vortices or gyrostats formed within 
the ether. Professor de Heen^ compares them to 
a rigid wire twisted into a helix, the direction of 
their rotations determining the attractions and 
repulsions. Sutherland seeks in the direction of 
the movements of these gyrostats the explanation 
of the electrical and thermal phenomena of con- 
duction. " Electric conduction," he says, " is due 
to the vibration of the gyrostats in the direction of 
the electric force, and thermal conduction to the 
vibration of vortices in all directions."^ 

It was mathematical analysis alone which led 
physicists to attribute a fundamental role to the 
vortices in the ether, but experiments made on 
material fluids give to this hypothesis a precise 
basis, since, as we shall see, they permit the repro- 
duction of the attractions and repulsions observed 
in electrical phenomena, and the constitution by 
vortices of material substances with geometric forms. 
A material vortex may be formed by any fluid, 
liquid or gaseous, turning round an axis, and by tne 
fact of its rotation it describes spirals. The study 
of these vortices has been the object of important 
researches by different scholars, notably by Bjerkness 
and Weyher.* They have shown that by them can 

1 Ether and Mattery 1900. 

' Prodromes d*tui Theorie de t Electriciti, Bruxelles, 1903. 
' " The Electric Origin of Rigidity," Philosophical Magazine^ May 
♦ Sur les iourbillons, 2nd edition. Paris, 1889. 


be produced all the attractions and repulsions 
recognized in electricity, the deviations of the 
magnetic needle by currents, etc. These vortices 
are produced by the rapid rotation of a central rod 
furnished with pallets, or, more simply, of a sphere. 
Round this sphere gaseous currents are established, 
dissymetrical with regard to its equatorial plane, and 
the result is the attraction or repulsion of bodies 
brought near to it, according to the position given to 
them. It is even possible, as Weyher has proved, to 
compel these bodies to turn round the sphere as do 
the satellites of a planet without touching it. 

These vortices constitute one of the forms most 
easily assumed by material particles, since a fluid can 
be caused to whirl by a simple breath. They can 
produce, besides, all the movements of rotation, and 
very stable equilibria capable of striving against the 
power of gravity as a top in motion remains upright 
on its pivot. It is the same with a bicycle, which falls 
laterally when it ceases to roll forward. The helices 
with vertical axes called helicopters used in certain 
processes of aviation rise in the atmosphere by screw- 
ing themselves into it so soon as they are put in 
rotation, and remain there so long as that rotation 
lasts. Directly they come to rest, being no longer 
able to struggle against gravity, they fall heavily to 
the ground. It will thus be easily conceived that it 
is in rotatory motion that is found the best explana- 
tion of the equilibria of atoms. 

It is by whirling movements in the ether that several 
authors also seek to explain gravitation. Professor 
Armand Gautier in a notice of my memoir on intra- 
atomic energy gives a similar explanation. If it 
could be considered as definitive, it would have the 


advantage of explaining the way in which the im- 
ponderable may go forth from the ponderable : — 

" The material atom animated by gyratory movements must 
transmit its gyration to the surrounding ether, and by it to the 
other distant material bodies which float in this ether. It fol- 
lows that, when the gyration passes from one to the other, the 
material bodies, by virtue of their own inertia, tend, so to speak, 
to screw themselves one on to the other by the intermediary of 
the common vortex of ether in which they are; in a word, these 
material bodies must attract one another. It is sufficient thus 
to admit that there must be a kind of viscosity between the 
particles of the ether, or rather a kind of transport {entrainemenf) 
of these particles one by the other. 

" But if the gyratory condition of the atomic edifices seems to 
be thus the cause of their mutual attraction — that is to say, of 
gravity, this latter must disappear wholly or in part if the energy 
of gyration be wholly or in part transformed into energy of 
translation in space. May it not likewise be the same with the 
electron — that is to say, with the atomuscule torn from the atom 
and launched forth from the material edifice with the velocity 
of the atominal light, in which atomuscule the speed of gyration 
has disappeared because transformed into speed of transla- 
tion? These electrons thus borrowed from matter, if no longer 
in a state of sensible or concordant gyration, may tlien lose all 
or part of their weight while keeping their mass, and while con- 
tinuing to follow the law which measures the energy transported 
by them by half the product of their mass multiplied by the 
square of their speed of translation.^ 

The experiments on whirling movements in 
fluids not only produce attractions, repulsions, and 
equilibria of all kinds: they may be associated so 
as to give birth to regular geometric forms as M. 
Benard^ has demonstrated in a series of experiments. 
He has shown that a thin layer of liquid subjected to 
certain perturbations (convection currents boirdering 

^ Revue Scientifique^ 13th January 1904. 
^^ Revue Ginirale des Sciences ^ 190a 


on stability) divides itself into vertical prisms with 
polygonal bases that can be rendered visible by 
certain optical processes or by simply mixing with it 
very fine powders. '* It is," says this author, " the 
geometric places of neutral vortices which form the 
plane walls of the hexagonal prisms and the vertical 
axes of these prisms. The lines of the whirl- 
pools are closed curves centred on the axis of these 
prisms." Metals suddenly chilled after having been 
fixed and cast in layers often divide in the same 
way and present to our observation polygonal cells.^ 
These experiments show us that the molecules of a 
liquid can assume geometrical forms without ceasing 
to be liquid. These momentary forms of equihbrium 
do not survive the causes which gave them birth. 
They are analogous to those I iiave been able to 
produce and render visible by properly combining 
the elements of dissociated matter, as we shall see 

Although the analogies between the molecules of 
material fluids and those of immaterial fluids are 
many, they never attain identity by reason of two 
capital dififerences between material aud imma- 
terial substances. The former are in fact subject to 
the action of gravity, and have very great mass. 
They therefore obey changes of motion, but rather 
slowly. The latter are free from gravity, and have 
very small mass, the smallness of this mass allowing 
them to take, under the influence of very feeble 
forces, rapid movements, and consequently to be 
extremely mobile. If, in spite of their feeble mass, 

^ According to Professor Quincke of Heidelberg, all substances on 
passing from the liquid to the solid state, form these cells, which he 
calls •* foam cells." — Proc, Ray. Soc,^ 21st July 1906 (A). 

* ■* * ^ ■* * ^ ^ 


the immaterial molecules can produce fairly great 
mechanical effects, such as are observed, for example, 
in Crookes' tubes, the mirrors of which become red 
hot under the action of the cathodic bombardment, it 
is because the smallness of the mass is compensated 

for by their extreme speed. In the formula T= , 

without changing the result, m can be reduced at will 
on condition that v is increased. 

By considering the important part played by the 
divers forms of equilibrium of which the ether is 
capable, it is easy to arrive at the conception that 
matter is nothing but a particular state of equilibrium 
of the ether. Consequently, when we seek in future 
chapters the links which unite material to immaterial 
things, we must especially examine the different forms 
of equilibrium possessed by that intermediary world 
of which we recognize the existence, and inquire into 
the analogies and dissimilarities offered by these 
equilibria when compared with the two worlds which 
we propose to unite. 





§ I. The First Interpretations. 

The ether and matter form the two extreme limits 
of the series of things. Between these limits, far as 
they are from each other, there exist intermediate 
elements, of which the existence is now revealed by 
observation. None of the experiments I shall set 
forth, however, will show us the transformation of 
the ether into material substances. It would require 
the disposal of colossal energy to effect such a con- 
densation. But the converse transformation of 
matter into the ether, or into substances akin to 
the ether, is, on the contrary, realizable, and can be 
realized by the dissociation of matter. It is in the 
discovery first of the cathode rays and then of the 
X rays that are found the germs of our present theory 
of the dissociation of matter. This dissociation, 
whether spontaneous or induced, always reveals 
itself by the emission into space of effluves identical 
with the cathode and the X rays. The assimilation 
of these two orders of phenomena, which for several 
years I was alone in maintaining, is to-day universally 



The discovery of the cathode and of the X rays 
which invariably accompany them, marks one of the 
most important stages of modern science. Without 
it, the theory of the dissociation of matter could never 
have been established; and without it, we should 
always have been ignorant that it is to this dissocia- 
tion of matter that we owe phenomena long known 
in physics, but which had remained unexplained. 
Every one knows at the present time what the 
cathode rays are. If through a tube furnished with 
electrodes and exhausted to a high vacuum an electric 
current of sufficient tension be sent, the cathode 
emits rays which are projected in a straight line, 
which heat such bodies as they strike, and which are 
deviated by a magnet. The metallic cathode only 
serves to render the rays more abundant, since I have 
proved by experiment that with a Crookes' tube 
without cathode or any trace of metallic matter 
whatever, exactly the same phenomena are observed. 

The cathode rays are charged with electricity, and 
can traverse very thin metallic plates connected with 
the earth without losing their charge. Every time 
they strike an obstacle they immediately give rise to 
those peculiar rays termed X rays, which differ from 
the cathode rays in not being deviated by a magnet, 
and pass through thick metallic plates capable of 
completely stopping the cathode rays.^ Both cathode 
and X rays produce electricity in all bodies that 
they meet, whether they be gases or solid matter, 
and consequently render the air a conductor of 

^ They also differ from the cathode rays in being, according to 
current theories, not streams of particles at all, but irregular move- 
ments or pulses in the ether. But see p. iii infra, — F. L. 


The first ideas of the nature of the cathode rays 
which were conceived were far different from those 
current to-day. Crookes, who first put in evidence the 
properties of these rays, attributed their action to the 
state of extreme rarefaction of the molecules of the 
gas when the vacuum had been carried very far. In 
this "ultra-gaseous" state, the rarefied molecules 
represented, according to him, a peculiar state which 
he described as a fourth state of matter. It was 
characterized by the fact that, no longer hindered in 
their course by the impact of the other molecules,* 
the free trajectory of the rarefied molecules lengthens 
to such a point that their reciprocal shocks become 
of no importance compared with their whole course. 
They can then move freely in every direction, and if 
their movements are directed by an external force 
such as the electric current of the cathode, they 
are projected in one direction only like grapeshot 
from a cannon. On meeting an obstacle they pro- 
duce by their molecular bombardment the effects of 
phosphorescence and heat, which the experiments 
of the illustrious physicist put in evidence. 

This conception, now recognized to be inexact, 
was inspired by the old kinetic theory of gases which 
I will thus recapitulate. The molecules of gases are 
formed of perfectly elastic particles, a condition 
necessary to prevent their losing energy by impact, 
and are far enough apart from each other to exercise 
no mutual attraction. They are animated by a speed 
varying with the gas, calculated at about 1,800 metres 
per second in the case of hydrogen, or about double 
that of a cannon-ball. This speed is also purely 
theoretical, for, by reason of their mutual impacts, 
the free path of each molecule is limited to about 


the thousandth part of a millimfetre. It is the 
impact of these molecules which produces the 
pressure exercised by a gas on the walls that 
enclose it. If the space enclosing the same volume 
of molecules be reduced to one-half, the pressure is 
doubled. It is tripled when the space is reduced 
to one-third. It is this fact which is expressed by 
the law of Mariotte. 

In a globe exhausted to a vacuum of the millionth 
of an atmosphere, things, according to Crookes, 
happen very differently. No doubt it still contains 
an enormous number of gaseous molecules, but the 
very great reduction in their number causes them to 
obstruct each other reciprocally much less than 
under ordinary pressure, and their free path is thus 
considerably augmented. If, under these conditions, 
a part of the molecules of air remaining in the tube 
be electrified and projected, as I said above, by 
an intense electric current, they may freely traverse 
space, and acquire an enormous speed; while, at 
ordinary pressure, this speed is kept down by the 
molecules of air encountered. 

The cathode rays, therefore, simply represented, in 
the original theory of Crookes, molecules of rarefied 
gas, electrified by contact with the cathode, and 
launched into the empty space within the tube at 
a speed they could never attain if they were ob- 
structed, as in gases at ordinary pressure, by the 
impact of other molecules. They were thought to 
remain, however, material molecules, not dissociated, 
but simply spread out, which could not change their 
structure. No one dreamed, in fact, at this epoch 
that the atom was capable of dissociation. 

Nothing remains of Crookes' theory since the 


measurement of the electric charge of the particles 
and of their mass has proved that they are a thousand, 
times smaller than the atom of hydrogen, the smallest 
atom known. One might doubtless suppose in strict- 
ness, as was done at first, that the atom was simply 
subdivided into other atoms preserving the properties 
of the matter whence they came; but this hypothesis 
broke down in face of the fact that the most dis- 
similar gases contained in Crookes' tubes gave 
identical products of dissociation, in which were 
found none of the properties of the substances from 
which they had issued. It had then to be admitted 
that the atom was not divided, but was dissociated 
into elements endowed with entirely new properties 
which were identical in the case of all substances. 

It was not, we shall see, by any means, in a day 
that the theory of dissociation just briefly indicated 
was established; in fact, it was clearly formulated 
only after the discovery of the radio-active substances 
and the experiments which helped me to prove the 
universality of the dissociation of matter. And it 
was only after several years that physicists at last 
recognized, conformably with my assertions, the 
identity of the cathode rays with the efBuves of 
particles emitted by ordinary substances during their 



§ 2. The Interpretations now current. 

At the time when only the cathode rays were 
known, the explanation by Crookes of their nature 
seemed to be quite sufficient. On the discovery of 
the X rays and of the emissions of the spontaneously 
radio-active bodies, such, as uranium, the insufficiency 
of the old theory was made clear. One of the mani- 


festations of the X rays and of the radio-active 
emissions which made the greatest impression on 
physicists and was the origin of the current explana- 
tions, was the production of electricity on all bodies 
both solid and gaseous struck by the new radiations. 
The X rays and the emissions from radio-active 
bodies possess, in fact, the common characteristic of 
producing something which renders the air and other 
gases conductors of electricity. With these gases 
thus made conducting we can, by passing them 
between the plates of a condenser, neutralize electric 
charges. It was, as a consequence, admitted that 
they were electrified. 

This was a very unforeseen phenomenon, for all 
earlier experiments had without exception shown 
that gases were not capable of being electrified. 
They can be kept, in fact, indefinitely in contact 
with a body electrified to a very high potential 
without absorbing any trace of electricity. If it 
were otherwise, no electrified surface — the ball of an 
electroscope, for instance — could retain its charge, and 
we were, therefore, in face of an entirely new fact, 
much more novel even than was at first thought, 
since it implied, in reality, the dissociation of matter, 
which nobody then suspected. 

So soon as an unforeseen fact is stated, one always 
tries to connect it with an old theory : — and since one 
theory alone, that of the ionization of saline solu- 
tions in electrolysis, gives an apparent explanation 
of the newly observed facts, haste was made to 
adopt it. It was therefore supposed that in a simple 
body there existed, as in a compound, two separable 
elements, the positive and negative ions, each 
charged with electricity of contrary sign. But 


the earlier theory of ionization only applied to 
compound bodies, and not to simple ones. The 
elements of compound bodies could be separated — 
or, as we now say, ionized, — chloride of potassium, 
for instance, being capable of separation into its 
chlorine ions and its potassium ions; but what 
analogy could exist between this operation and the 
dissociation of chloride or potassium itself, since it 
was considered a fundamental dogma that a simple 
body could not be dissociated. There 'was all the 
less analogy between the ionization of saline solu- 
tions and that of simple bodies, that, when the 
elements of a salt are separated by the electric 
current, very different bodies are extracted according 
to the compound dissociated. Chloride of potassium, 
mentioned above, gives chlorine and potassium ; with 
sodium oxide, oxygen and sodium are obtained, and 
so on. When, on the other hand, we ionize a simple 
body, we extract from it always the same elements. 
Whether it be hydrogen, oxygen, nitrogen, aluminium 
or any other substance, the substance extracted is 
the same every time. Whatever may be the body 
ionized, and whatever the mode of ionization, one 
obtains only those particles — ions or electrons — of 
which the electric charge is the same in all bodies. 
The ionization of a saline solution and that of a simple 
body, such as a gas, for instance, are therefore two 
things which present, in reality, no analogy to each 

From the verification of the fact that from simple 
bodies such as oxygen, hydrogen, etc., only the same 
elements can be extracted, it might easily have been 
deduced: — first, that atoms can be dissociated; and 
secondly, that they are all formed of the same elements. 


These conclusions are now evident, but they were a 
great deal too much outside the ideas then dominant 
for any one to dream of formulating them. 

The term ionization when applied to a simple body 
had no great meaning, but it formed the beginning 
of an explanation, for which reason it was eagerly 
accepted. I shall likewise accept it, in order not 
to confuse the reader's mind, but at the same 
time shall take care to remark that the term 
ionization applied to a simple body merely means 
dissociation of its atoms, and not anything else. 

Several physicists, it is true, and I am astonished 
to find Rutherford among them, think that the 
ionization of a gas can take place without in any 
way changing the structure of its atoms. One 
cannot see why that which is admitted to be exact 
in the case of a solid body should be otherwise for 
a gaseous one. We know that by divers means we 
can dissociate any simple body whatever. In the 
case of radium, aluminium, oxygen, or any other 
substance, the products of this dissociation are 
particles which are admitted to be exactly identical 
in the case of all bodies. There is therefore no 
foundation for saying that one has dissociated some 
substances and not others. To take something from 
an atom is always to begin its dissociation. Gases, 
on the other hand, are the easiest of all bodies 
to dissociate, because, to accomplish this, it is 
only necessary to pass electric discharges through 

This ionization of simple bodies — that is tp say, 
the possibility of extracting from them positive and 
negative ions bearing electric charges of opposite 
signs — once admitted, presented a number of difl&- 


culties, which were studiously passed over in 
silence, because it is really impossible to find their 
explanation. For these electric ions, or this ionic 
electricity, if I may use the expression, differs singu- 
larly in its properties from the ordinary electricity 
which a century of researches has made known to us. 
A few comparisons will suffice to show this. On 
any insulated body whatever we can fix only a 
very small quantity of electricity if it is a solid, and 
none at all if it is a gas. Ionic electricity, on the 
other hand, must necessarily be condensed in 
immense quantities on infinitely small particles. 
Ordinary electricity, even though it has the intensity 
of lightning, can never pass through a metallic plate 
connected with the earth, as Faraday showed long 
ago. On this classic property there has even been 
founded the manufacture of clothes from light 
metallic gauze which affords the workmen in fac- 
tories, where electricity at a high potential is pro- 
duced, protection from even the most violent 
discharges. Ionic electricity, on the other hand, 
easily traverses metallic enclosures. Ordinary 
electricity goes along wire conductors with the 
rapidity of light, but cannot be led like a gas into 
a hollow tube bent back upon itself. Ionic electricity, 
on the other hand, acts like a vapour, and can cir- 
culate slowly through a tube. And finally, ionic 
electricity has the property of giving birth to the 
X rays whenever the ions animated by a certain 
speed happen to touch any body whatever. 

No doubt it can be urged that electricity gene- 
rated by the ionization of matter which has 
assumed the special form of electrical atoms, must 
possess in this form properties very different to 


ordinary electricity. But then, if the properties of 
the atom called electrical are absolutely different 
to electricity, why call it electrical ? In the ex- 
periments I shall set forth, electricity will most 
often appear to us as an effect and not a cause. It 
is to this unknown cause what electricity is to the 
heat or to the friction which generates it. When a 
rifle-ball or a jet of steam produces electricity by 
its impact, we do not say that this bullet or this 
jet of steam are electricity, nor even that they are 
charged with it. The idea would never enter any 
one's head of confounding effect with cause as some 
persist in doing in the case of the radio-active 

The phenomena observed in the dissociation of 
matter, such as the emission of particles having a 
speed of the order of light and the property of 
generating X rays, are evidently characteristics 
possessed by none of the known forms of electricity, 
and ought to have led physicists to suppose, as I did, 
that they are certainly the consequence of an entirely 
new form of energy. But the imperious mental need 
of seeking for analogies, of comparing the unknown 
with the known, has led to the connecting of these 
phenomena with electricity, under the pretext that 
among the effects observed one of the most constant 
was the final production of electricity. 

It is plain, however, that several physicists are 
very near arriving by different roads at the conception 
that all these radio-active emissions which it is 
sought to connect with electricity by the theory of 
ionization, represent manifestations of intra-atomic 
energy — that is to say, of an energy which has no 
relation to anything known; and the facts proving 


that electricity is only one of the forms of this energy 
are multiplying daily. 

One of the most important of these is the discovery 
due to Rutherford, of which I shall soon have to 
speak, namely, that the greatest part of the particles 
emitted during radio-activity proceed from an eman- 
ation possessing absolutely no electric charge, though 
capable of giving birth to bodies able to produce 
electricity. Emanations, ions, electrons, X rays, 
electricity, etc., are really, as we shall see, only 
different phases of the dematerialization of matter — 
that is to say, of the transformation of intra-atomic 

"It seems," wrote Professor de Heen with regard to my ex- 
periments, "that we find ourselves confronted by conditions 
which remove themselves from matter by successive stages of 
cathode and X ray emissions and approach the substance which 
has been designated the ether. The ulterior researches of 
Gustave Le Bon have fully justified his first assertions that all 
these effects depend upon a new mode of energy. This new 
force is as yet as little known as was electricity before Volta. 
We simply know that it exists." 

But whatever may be the interpretations given to 
the facts revealing the dissociation of matter, these 
facts are incontestable, and it is only the demon- 
stration of them which is at present of importance. 

On these facts there is almost complete agreement 
at the present time, and it is the same with the 
identity of the products of the dissociation of matter, 
whatever be the cause of this dissociation. Whether 
they are generated by the cathode of Crookes' tube, 
by the radiation of a metal under the action of light, 
or by the radiation of spontaneously radio-active 
bodies, such as uranium, thorium, and radium, etc.. 


the efHuves are of the same nature. They are subject 
to the same magnetic deviation, the relation of their 
charge to their mass is the same. Their speed alone 
varies, but it is always immense. 

We can, then, when we wish to study the dis- 
sociation of matter, choose the bodies in which the 
phenomenon manifests itself most intensely — either, 
for example, the Crookes' tube, in which a metallic 
cathode is excited by the electric current of an 
induction coil, or, more simply, very radio-active 
bodies such as the salts of thorium or of radium. 
Any bodies whatever dissociated by light or other- 
wise give, besides, the same results, but the dis- 
sociatioh being much weaker, the observation of the 
phenomena is mdte difficult. 



§ I. Classification of the Prodmts of the Dematerializa- 

tion of Matter. 

I HAVE set forth in the preceding chapter the genesis 
of the current ideas on the interpretation of the 
facts relating to the dissociation of matter. We 
will now study the characteristics of the products of 
this dissociation. Not to complicate a subject 
already very obscure, I will accept, without dis- 
cussion, the theories at ptesent admitted, and will 
confine myself to the attempt to state them with 
more precision, and to bring together things which 
resemble one another, but which are often called by 
different names. 

- I have said that, whatever the body dissociated 
and the mode of dissociation employed, the products 
of this dissociation are always of the same nature. 
Whether it be the emissions of radium, of those of 
any metal under the influence of light, of those 
produced by chemical reaction or by combustion, 
or of those proceeding from an electrified point, 
etc., the products will,. as already said, be identical, 
although their quantity and their speed of emission 
may be very different. 
This generalization has taken a long time to 

113 8 


establish. It was, consequently, natural that things 
recognized later on as similar after having first been 
considered as different, should have been designated 
by particular terms. It is therefore clearly important 
to define first of all the exact value of the various 
terms employed. Without exact definitions no 
generalization is possible. The necessity of such 
definitions makes itself all the more felt that the 
greatest confusion exists in the meaning of the terms 
generally in use. It is easy to see, moreover, why this 
should be so. A new science always gives birth to 
a new terminology. The science is not even con- 
stituted until its language has been fixed. The 
recently discovered phenomena necessarily compelled 
the formation of special expressions indicating both 
the facts and the theories inspired by those facts. 
But, these phenomena having been examined by 
various inquirers, the same words have sometimes 
received very different meanings. 

Often words of old standing and possessing a well- 
defined meaning, have been used to designate things 
newly discovered. Thus, for instance, the same 
word ion is used to designate the elements separated 
in a saline solution and those derived from the dissocia- 
tion of simple bodies. Some physicists, like Lorentz, 
use indifferently the terms ions and electrons, which 
to others imply very distinct things. J. J. Thomson 
calls corpuscles^ the electric atoms which Larmor 
and other authors call electrons, etc. 

By only taking into account facts revealed by experi- 
ment and without troubling about the theories from 
which the definitions are derived, we find that the 

1 The corpuscles of Professor J. J. Thomson are, of course, the 
negative electrons only. — F. L, 


diiferent products of the dissociation of matter now 
known may be arranged in the six following classes: 
— 1st, Emanations; 2nd, Negative Ions; 3rd, Positive 
Ions; 4th, Electrons; 5th, Cathode rays; 6th, X rays 
and analogous radiations. 

§ 2. Characteristics of the Elements furnished by the 

Dissociation of Matter. 

The Emanation, — This product, which we shall exa- 
mine at greater length in the chapter devoted to the 
study of spontaneously radio-active matter, is a semi- 
material substance having some of the characteristics 
of a gas, but is capable of spontaneously disappear- 
ing into electric particles. It was discovered by 
Rutherford in thorium and by Dorn in radium, and 
according to the researches of J. J. Thomson^ it 
exists in the majority of ordinary bodies: water, sand, 
stone, clay, etc. It may, then, be considered as one of 
the usual stages of the dissociation of matter. 

If we have just styled a semi-material substance 
"the emanation," it is because it possesses at once 
the properties of material bodies and those of bodies 
which are not material or which have ceased to be so. 
It can be condensed, like a gas, at the temperature 
of liquid air, when, thanks to its phosphorescence, its 
behaviour can be watched. It can be kept for some 
time in a sealed glass tube, but it soon escapes by 
transforming itself into electric particles^ and then 

^ See the Cambridge Philosophical Society's Proceedings for April 1904, 
pp. 391 et seq.. Professor Thomson there suggests that the emanation in 
the substances examined by him may be due to the presence of some 
radio-active impurity. — F. L. 

"^ According to Mr. Soddy (Radio-aclivily^ p. 163), there is some 
reason to think that the disappearance of the helium is caused by the 
projected a particles burying themselves in the glass. — Y. L. 


ceases to be material. These electric particles com- 
prise positive ions (Rutherford's a rays), to which, after 
a certain time, succeed electrons (the same author's P 
rays) and X rays (y rays). These various elements 
will be studied later on. 

Although the "emanation" can produce electric 
particles by its dissociation, it is not charged with 

Positive Ions and Negative Ions. — Let us recall 
to mind, for the understanding of what is to follow, 
that, according to a theory already old, which has, 
however, taken a great extension in these days, all 
atoms contain electric particles of ascertained size, 
called electrons. Let us now suppose that a body 
of some kind, a gas, for example, is dissociated — 
that is to say, ionized, as it is called. According to 
present ideas, there would be formed within it 
positive ions and negative ions by a process com- 
prising the three following operations : — 

ist. The atom, originally neutral — that is to 
say, composed of elements which neutralize each 
other — loses some of its negative electrons. 2nd. 
These electrons surround themselves, by electro- 
static attraction, with some of the neutral molecules 
of the gases around them in the same way that 
electrified bodies attract neighbouring ones. This 
aggregate of electrons and neutral particles form the 
negative ion. 3rd. The atom, thus deprived of part 
of its electrons, then possesses an excess of positive 
charge, and in its turn surrounds itself with a 
retinue of neutral particles, thus forming the positive 
ion. Such is — reduced to its essential points — the 
present theory which the researches of numerous 


experimenters, especially J. J. Thomson, have suc- 
ceeded in getting adopted, notwithstanding all the 
objections raised against it. 

Things, however, only happen in the manner 
described in a gas at ordinary pressure. In a 
vacuum, electrons do not surround themselves with 
a retinue of material molecules; they remain in 
the state of electrons and can acquire a great speed, 
so that the formation of negative ions is not 
observed in a vacuum. Nor does the positive ion 
in a vacuum surround itself with neutral particles, 
but, as it is composed of all that is left of the atom, 
it is still voluminous, which is why its speed is 
comparatively feeble. 

It may happen, however, and this is the case 
with the emission from radio-active bodies, that the 
negative electrons are expelled from the atom into 
the atmosphere, at the ordinary pressure, with too 
great a speed for their attraction on the neutral 
molecules to be capable of exercise. They do not 
then transform themselves into ions, but remain in 
the state of electrons and circulate as rapidly as 
those emitted in vacuo. It is they that form the 
/3 rays of Ruthetford. 

The positive ions, notwithstanding their volume, 
are likewise capable of acquiring a very high speed 
in the case of the emission from the radio-active sub- 
stances. At least, such is the result of the researches 
of Rutherford, who supposes that the a rays— which 
constitute 99 per cent, of the emission of radium^ — are 
formed of positive ions launched with a speed equal 
to one-tenth that of light. This point demands 
elucidation by further researches. 

When the factors of pressure and speed do not 



intervene, and the negative and positive ions are 
formed at atmospheric pressure, they have about 
the same bulk. It is only when they are generated 
in vacuo or are emitted with a very high speed that 
their dimensions vary considerably. In vactw, in 
fact, the electron, as the nucleus of the negative 
ion, does not, as mentioned above, surround itself 
with material molecules, and remains in the state 
of electron. Its mass, according to several measure- 
ments of which I shall have to speak elsewhere, does 
not exceed the thousandth part of that of an atom of 
hydrogen. What remains of the atom deprived of 
a part of its electrons — that is to say, the positive 
ion — possesses a mass equal to and sometimes greater 
than that of an atom of hydrogen, and consequently 
at least a thousand times greater than that of the 

It is therefore necessary, when treating of the 
properties of ions, to distinguish — ist, whether they 
were formed in a gas at ordinary pressure; 2nd, if 
they were generated in vacuo ; 3rd, if, by any cause 
whatever, they were launched into space at a great 
.speed at the moment of their formation. Their pro- 
perties naturally vary according to these different 
cases, as we shall see in other parts of this work. 
But, in all these different cases, the general structure 
of the ions remains the same. Their fundamental 
nucleus is always formed of electrons — that is, of 
electric atoms. 

It is natural to suppose that the dimensions and 
properties of the ions formed in a gas at ordinary 
pressure differ notably from those of the electrons, 
since these latter are supposed to be free from all 
admixture of matter. But it seems difficult, on the 


currqat theory, to explain some of the properties 
of the ions, especially those which can be observed 
with simple gases, bodies which are easy to ionize 
by many different means. It is noted that they then 
form in the aggregate an entirely special fluid of 
which the properties are akin to those of a gas, 
without, however, possessing its stability. It can 
circulate, for some time, before being destroyed, 
through a worm of metal connected with the earth, 
which electricity could never do. It possesses a 
marked inertia, as its slight mobility proves. . Such a 
fluid has properties too peculiar not to have a name 
given to it, for which reason I propose to call it the 
ionic fluid. We shall see that, owing to its inertia, 
we can transform it into very regular geometrical 

As ions are charged with electricity, they can be 
attracted by electrified bodies. This is, in fact, as 
we shall see later, the means of measuring their 
charges. When an ionized gas is enclosed between 
twO' metal plates, one of which bears a positive and 
the other a negative charge, the first-named attracts 
the negative and the last the positive ions. If the 
voltage of these plates is weak, part of the ions com- 
bine with one another, and become neutral, especially 
when their number is considerable. To extract them 
from the gaseous medium before they combine, it is 
necessary to raise the voltage of the containing vessel 
until the current produced by the circulation of the 
ions no longer increases — which maximum current is 
called the " saturation current." 

We shall likewise see, in the part of this work 
devoted to experiments, that if ions possess common 
properties, which allow them to be classed in the 


same family, they also possess certain properties 
which permit them to be sharply differentiated. 


Electrons. — The electrons, or electric atoms — called 
"corpuscles" by J. J. Thomson — are, as we have 
seen, the nucleus of the negative ion. They are 
obtained, disengaged from any foreign element, by 
means either of Crookes' tubes (when they take the 
name of cathode rays) or of radio-active bodies (when 
they are terrned P rays). But, in spite of these 
differences of origin, they appear to possess similar 

One of the most striking properties of electrons 
— apart from that of generating X rays — is that of 
passing through metallic plates without losing their 
electric charge, which, I repeat, is contrary to a 
fundamental property of electricity. The most 
violent discharges are, as is well known, incapable 
of passing through a metallic plate, however thin, 
connected with the earth. 

These electrons, presumed to be atoms of pure 
electricity, have a definite size (and probably also a 
considerable rigidity). They have, whatever their 
origin, an identical electric charge, or can, at least, 
produce the neutralization of an amount of electricity 
which is always the same. But we possess no means 
of studying them in repose; and they are only known 
to us by the effects they produce when animated by 
great speed. 

Their apparent mass — that is to say, their inertia — 
is, as we shall see in another chapter, a function of 
their speed. It becomes very great, and even infinite, 
when this speed approaches that of light. Their 
real mass, if they have one in repose, would therefore 


be only a fraction of the mass they possess when in 

The measurements of the inertia of electrons have 
only been made with the negative electrons, the only 
ones which have yet been completely isolated from 
matter. They have not been effective with the positive 
ions. Being inseparable at present from matter, 
these last must possess its essential property — that 
is to say, a constant mass independent of speed. 

Electrons in motion behave like an electric current, 
since they are deviated by a magnetic field, and their 
structure is much more complex, in reality, than the 
above summary would seem to indicate. Without 
going into details, I shall confine myself to saying 
that they are supposed to be constituted by vortices 
of ether analogous to gyroscopes. In repose, they 
are surrounded by rectilinear rays of lines of force. 
In motion, they surround themselves with other lines 
of force — circular, not rectilinear — from which result 
their magnetic properties. If they are slowed down 
or stopped in their course they radiate Hertzian 
waves, light, etc. I shall recur to these properties in 
summing up in another chapter the current ideas on 

The Cathode Rays, — As has been said in a preceding 
chapter, physicists have greatly altered their views 
as to the nature of the cathode rays. They are now 
considered to be composed of electrons — that is to 
say, of atoms of pure electricity disengaged from 
all material elements. They are obtained by 
various processes, notably by means of radio-active 
substances. The simplest way to produce them in 
large quantities is to send an induction current 
through a glass bulb furnished with electrodes and 


exhausted to the millionth of an atmosphere. As 
soon as the coil begins to work, there issues from 
the cathode a sheaf of rays, termed cathodic, which 
can be deviated by a magnet. 

The bombardment produced by these rays has 
as its consequence very energetic effects, such as the 
fusion of metals struck by it. From their action on 
the diamond, the temperature they generate has been 
calculated at 3,500' C. Their power of penetration is 
rather weak, whereas that of the X rays, which are 
derived from them, is, on the contrary, very great. 
Lenard, who was the first to bring the cathode rays 
outside a Crookes' tube, employed to close the orifice 
in the tube, a plate of aluminium only a few thousands 
of a millimetre in thickness. 

A portion of the electric particles constituting 
the cathode rays is charged with negative electricity; 
the other — that produced in the most central part 
of the tube — is composed of positive ions. These 
last have been called "Canal rays." The cathode 
rays and the canal rays of Crookes' tubes are of the. 
same composition as the a and /? radiations emitted 
by radio-active bodies such as radium and thorium. 

Cathode rays possess the property of rendering 
air a conductor of electricity and of transforming 
themselves into X rays so soon as they meet an 
obstacle. In the air they diffuse very speedily, differ- 
ing in this from the X rays, which have a strictly 
rectilinear progress. When Lenard brought the 
cathode rays out of a Crookes' tube through a plate 
of thin metal, he noted that they formed a widely- 
spread fan which did not extend farther than a few 
centimetres. In very rarefied gases it is possible, on 
the other hand, by means of a diaphragm, to confine 


them to a cone free from diffusion for the length 
of a m^tre. 

Whatever the gas introduced into a Crookes' tube 
before creating the vacuum — a very relative vacuum 
since there still remain in it thousands of millions 
of molecules, even when the pressure is reduced to 
the millionth of an atmosphere — it is noted that 
the cathode rays which are formed have the same 
properties and the same electric charges. J. J. 
Thomson has concluded from this that the atoms of 
the most different bodies contain the same elements. 
If, instead of a Crookes' tube, a very radio-active 
matter, thorium or radium, is used, the majority of 
the proceeding phenomena are found with simply 
quantitative variations. For example, more rays 
charged with negative electricity are found in the 
Crookes' tube than in those emanations of radium 
which are especially charged with positive electricity; 
but the nature of the phenomena observed in the 
two cases remains the same. 

Speed and Charge of the Cathode and Radio-active 
Particles, — The measurement of the speed and of 
the electric charge of the particles of which both 
bodies are found, has proved, as has just been said, 
the cathode rays and the emission from radio-active 
their identity. It would take long to set forth the 
divers methods which have settled these points. 
Details will be found in the memoirs of J. J. 
Thomson, Rutherford, Wilson, etc. I will only here 
indicate very briefly the principle of the methods 

So far as the speed, which is of the same order as 
that of light, is concerned, it may seem very difficult 
to measure the velocity of bodies moving so quickly; 


yet it is very simple. A narrow pencil of cathodic 
radiations obtained by any means — for example, from 
a Crookes' tube or a radio-active body — is directed 
on to a screen capable of phosphorescence, and on 
striking it a small luminous spot is produced. 
This sheaf of particles being electrified can be 
deviated by a magnetic field. It can therefore be 
deflected by means of a magnet so disposed that 
its lines of force are at right angles to the direction 
of the particles. The displacement of the luminous 
spot on the phosphorescent screen indicates the de- 
viation which the particles undergo in a magnetic 
field of known intensity. As the force necessary to 
deviate to a given extent a projectile of known 
mass enables us to determine its speed, it will 
be conceived that it is possible to deduce from 
the extent of their deviation the velocity of the 
cathodic particles. It is seldom less than one-tenth 
of that of light, or say 30,000 kilometres per second, 
and sometimes rises to nine-tenths. When the pencil 
of radiations contains particles of different speed, they 
trace a line more or less long on the phosphorescent 
screen instead of a simple point, and thus the speed 
of each can be calculated. 

To ascertain the number, the mass, and the electric 

charge — or at least the ratio — of the charge to the 

mass — of the cathode particles, the procedure is as 
follows: — The first thing is to ascertain the electric 
charge of an unknown number of particles contained 
in a known volume of gas. A given quantity of gas 
containing the radio-active particles is then enclosed 
between two parallel metallic plates, the one in- 
sulated and the other positively charged. The 


positive particles are repelled towards the insulated 
plate, while the negative particles are attracted, and 
their charge can be measured by the electrometer. 
From this total charge, the charge of each particle 
can evidently be deduced if the number of particles 
can be ascertained. 

There are several modes of arriving at this number. 
The most simple, first used by J. J. Thomson, is 
based on the fact that when cathode particles are 
introduced into a reservoir containing water-vapour, 
each particle acts as a condensation nucleus for the 
vapour and forms a drop. The result is a cloud of 
small drops. These latter are . far too small 
to be counted, but their number may be de- 
duced from the time they take to fall through the 
recipient containing them, the fall being rendered 
very slow owing to the viscosity of the air. . When 
one knows the number of these small drops, and con- 
sequently the number of cathode particles contained 
in a given volume of water-vapour, and also the 
electric charge of all the particles, a simple sum in 
division gives the electric charge of each particle. 

It is by working in this way that it has been 
possible to demonstrate that the electric charge of 
the cathode particles was constant wha'e/er their 
origin (particles of radio-active bodies, of ordinary 
metals struck by light, etc.). Their electric charge 
is represented by about lo^ electro-magnetic units. 

The value of — of the ion of hydrogen in the 


electrolysis of liquids being only equal to lo*, it 
follows that the mass of the negative ion in dis- 
sociated bodies is the thousandth part of the atom 
of hydrogen, the smallest atom known. 


The preceding figures only apply to negative ions. 
They are the only ones of which the size is constant 
for all substances. As to the positive ions which 
contain the greater part of the undissociated atom, 
their charge naturally varies according to the sub- 
stance. Their dimensions are never less than those 
of the atom of hydrogen. 

■ The X rays. — When the cathode rays— that is to 
say, the electrons emitted by a Crookes' tube or by a 
radio-active body, meet an obstacle, they give birth 
to special radiations called X rays when they come 
from a Crookes' tube, and y rays when emitted by 
a radio-active body. These radiations travel in a 
straight line, and can pass through dense obstacles. 
They are not reflected, refracted, nor polarized, and 
this absolutely differentiates them from light. They 
are not deviated by a magnet, and this separates 
them sharply from the cathode rays, whose power 
of penetration is, besides, infinitely more feeble. 
The X or 7 rays possess the property of rendering air 
a conductor of electricity, and consequently of dissi- 
pating electric charges. They render phosphorescent 
various substances, and impress photographic plates. 

When the X rays strike any substances whatever, 
they cause the formation of what are called secondary 
rays, identical with the cathode rays;^ this simply 
means that X rays derived from the dissociation of 
matter have the property of producing a further 
dissociation of matter when they come into contact 
with it, a property which luminous radiations, 

^ According to Professor Sagnac, only a part of the secondary rays 
are deviable in a magnetic field, and this part varies according to the 
metal or other substance by which they are emitted. {CompUs rendus 
lilt 1st Congres International pour la Kadiologic, BruxeUes, 1905, 
pp. 146 ct seqJ) — F. L. 


notably those of the ultra-violet region, likewise 

Notwithstanding the researches of hundreds of 
physicists ever since their discovery, our knowledge 
concerning the X rays is almost solely confined to 
the notice of the attributes described; and as they 
have no relation to anything known, they can be 
assimilated to nothing.^ 

It has been sought, however, to connect them with 
ultra-violet light, from which they would only differ 
by the extreme smallness of their wave-length. 
This hypothesis seems to have but small grounds 
for support. Without going into the speed which 
the cathode rays must possess to impart to the ether 
vibrations corresponding to those of light, and leav- 
ing on one side the absence of polarization and of 
refraction which would be justified by the smallness 
of the supposed waves, it is curious to observe that 
the more one advances into the ultra-violet region, 
and the nearer one consequently gets to the supposed 
wave-length of the X rays, the less penetrating do 
the radiations become. In the extreme limit of the 
spectrum they end by being no longer able to over- 
come the slightest obstacle. For the extreme violet 
spectrum in the neighbourhood of .160/A to .100/*, so 
lately studied by Schumann and Lenard, two centi- 
mfetres of air are as opaque as lead, as is a sheet of 
mica the hundredth part of a millimetre in thickness. 

^ For further particulars of this analogy see C. Sagnac, VOptique 
des Rayons X^ p. 140; Paris, 1900. — F. LI 

' Professor Soddy compares them to light, both being, according to 
him, pulses in the ether, and attributes the impossibility of their 
polarization, etc., to the fact that, unlike light, they are ''sudden 
pulses very rapidly dying away " instead of regular successive undula- 
tions, Cf. H(idiQ'4ctivity^ p. 8. — F, I^ 


Now, the X rays, supposed to be so near to this 
extreme region of the ultra-violet, pass, on the 
contrary, through all obstacles, thick metallic plates 
included. If they did not produce fluorescence and 
photographic action, no one would have dreamed 
of comparing them to ultra-violet light. 

The impossibility of giving to the X rays that 
deviation by a magnetic field which the cathode 
rays undergo, has caused them to be looked upon 
as no longer possessing any electricity, but this 
conclusion may easily be contested. Suppose, in 
fact, that the X rays are constituted of electric atoms 
still more minute than the ordinary negative electrons, 
and that their speed of propagation borders on that of 
light.^ According to the researches to be presently 
mentioned, electrons having such a velocity would 
have an infinite mass. Their resistance to motion 
being infinite, it is evident that they could not be 
deviated by a magnetic field, though composed of 
electric elements. 

What seems now to be most evident is that there 
is no more reason to connect the X rays with 
electricity than with light. Assimilations such as 
these are the offspring of that habit of mind which 
induces us to connect new things with those 
previously known. The X rays simply represent 
one of the manifestations of intra-atomic energy 
liberated by the dissociation of matter. They con: 
stitute one of the stages of the vanishing of matter, 
a form of energy having its own characteristics, 
which must be defined solely by these characteristics 

^ The Austrian physicist, Professor Marx, claims to have measured 
their speed, and to have ascertained that it is the same as that of light. 
(Annaien der Physik, 1905).— F. L. 


without endeavouring to fit it into previously 
arranged categories. The universe is full of un- 
known forces which, likfe the X rays of to-day, and 
the electricity of a century ago, were discovered only 
when we possessed reagents capable of revealing 
them. Had phosphorescent bodies and photographic 
plates been unknown, the existence of X rays could 
not have been verified. Physicists handled Crookes' 
tubes, which yield thesfe rays in abundance, for a 
quarter of a century without discovering them. 

If it is probable that the X rays have their seat in 
the ether, it seems certain that they are not constituted 
by vibrations similar to those of light. To me, they 
represent the extreme limit of material things, one of 
the last stages of the vanishing of matter before its 
return to the ether. 

Having sufficiently described, according to present 
ideas, the supposed constitution of the products 
given off by matter during its dissociation, we will 
now study the various forms of this dissociation, and 
show that we shall everywhere meet again the ele- 
ments just enumerated. 



§1. The Products of the Dematerialization of very Radio- 
active Substances. 

We are about to relate, in this chapter, the researches 
which have been effected on very radio-active sub- 
stances — that is to say, upon substances which 
dissociate spontaneously and rapidly. Among the 
products of their dematerialization we shall again 
meet with those which are given off by any substance 
dissociated by any means, but the products emitted 
will be much greater in quantity. Under different 
names we shall still find the emanation, ions, elec- 
trons, and X rays. 

It must not be thought that these substances repre- 
sent all the stages of the dematerialization of matter. 
Those of which the existence is known are only 
parts of what is probably a very long series. 
If we always meet with the same elements in the 
products of all bodies subjected to dissociation, it is 
because the reagents actually in use, being only 
sensitive to certain substances, are naturally unable 
to reveal others. When we discover other reagents, 
we shall certainly note the existence of other 

The very great interest of the spontatieously radio- 
! 130 


active substances consists in their emitting, in con- 
siderable quantity, elements which other bodies only 
produce in much smaller 
quantity. By thus enlarg- 
ing a general phenomenon, 
they permit of its being 
studied more in detail. 

In this chapter we shall 
simply set forth the re- 
searches on eminently 
radio-active bodies, thorium 
and radium in particular. 
It is as yet a very new sub- 
ject, and for that reason the 
results obtained will offer 

many contradictions and rh. tkj^lrd's ^ radi^tUn, 
uncertainties. Their im- imitud by a radio-adivi body aud 
portance is, however, para- uparated by a magnetu field. 

mount. °" ""^ '"^' '"^ "*'" "" " •^^''" 
T> .L r J L L lions (or positive ions), which form 
Rutherford, who has ggo,„f,h^t„,„,„di^,i„„,.„„,he 
studied the radio - active Hghl the fi radiations (or n^alive 
substances with great sue- electrorsj; and in the centre, un- 
cess, and has, with Curie, deviated by the n^agn^ic field "he 
' ' I, ^, T o' X rays. This mode of re- 
discovered nearly all the picsenlalion has been borrowed 
facts concerning them, has fiom Rutherford and Curie, hut 
designated their radiations the relation between the various 
, ° , ,, , radiations has been modified, so as 
by the letters a, ^, and y, ,„ .^ow plainly that the a rays 
which are now generally form the greatest part of the radia- 
adopted. But under these "on^. The diagrams hitheno 
11 .. r J published show precisely the 
new appellations are lound "^ ' ' 

exactly the products we 

have described. The « radiations are composed of 
positive ions, the /3 radiations of electrons identical 
with those constituting the cathode rays, while the y 


radiations are similar to the X rays. These three 
kinds of radiations are very clearly indicated iii the 
diagram given in Fig. 3. 

To these several radiations is joined, as a primary 
phenomenon, according to Rutherford, the emission 
of a semi-material substance, which he terms ''emana- 
tion/' It possesses no electric charge, but would 
appear to undergo subsequent stages of dissociation, 
which change it into a and P particles. We will 
now examine the properties of the products we have 
just enumerated. For the most part, we shall only 
have to repeat or complete what has been said in a 
previous chapter. 

§ 2. a RaySy or Positive Ions. 

The a rays are formed of positive ions. They 
are deviated by an intense magnetic field, but in a 
contrary direction to the /? rays. The radius of curva- 
ture of their deviation is 1000 times greater than 
that of the P particles. They form 99% of the total 
radio-activity of radiuni. They render air a con- 
ductor of electricity. Their action on a photo- 
graphic plate is much less than that of the ^ rays, 
and their force of penetration very slight, since they 
are stopped by a sheet of paper. This weak power 
of penetration enables them to be easily differentiated 
from the other radiations to which paper is no 
obstacle. Of all the emissions of radio-active bodies 
it is the a rays especially which make the air a 
conductor of electricity, and it is the p rays which 
produce photographic impressions. When a radio- 
active body is enclosed in a glass tube nearly all the 
a particles are stopped by the glass walls. 


It is supposed, from various calculations, that the 
a particles must have a mass equal or superior to 
that of the hydrogen atom and a like charge. Their 
speed, as calculated from the extent of their deviation 
by a magnetic field of given intensity, is one-tenth 
that of light. Their quantity varies according to 
the substance. For uranium and thorium it is, for 
one gramme, 70,000 per second, and for radium a 
hundred thousand millions. This emission may last 
without interruption for more than a hundred years. 

The emission of the a particles, otherwise positive 
ions, is, together with the production of the emana- 
tion, the fundamental phenomenon of radio-activity. 
The emission of P particles and that of the 7 rays, 
w^hich together form hardly one per cent, of the total 
emission, should represent a further stage in the 
dissociation of radib-active atoms. 

On striking phosphorescent bodies the a particles 
render them luminous. It is on this property that is 
based the spinthariscope, an instrument which renders 
visible the permanent dissociation of matter. It 
simply consists of a screen of sulphide of zinc, above 
which is placed a small metal rod, the end of which 
has been dipped in a solution of chloride of radium. 
On examining the screen through a magnifying-glass, 
there can be seen spurting out without cessation a 
shower of small sparks produced by the impact of 
the a particles, and this emission may last for 
centuries, which shows the extreme smallness of the 
particles coming from the disaggregation of atoms. 
If this emission is visible, it is, as Crookes says, be- 
cause " each particle is made apparent solely through 
the enormous degree of lateral perturbation produced 
by its shock on the sensitive surface, in the same way 


that raindrops falling into the water produce ripples 
which exceed their diameter." I have succeeded, by 
using certain varieties of phosphorescent sulphide, in 
making screens allowing the phenomenon of dissocia- 
tion to be observed, not only with salts of radium, 
but also with divers substances, notably thorium 
and uranium.^ 

The high speed of the a particles seems very diffi- 
cult to explain. This speed is intelligible enough in 
the case of the P rays, which, being composed of atoms 
of pure electricity, and having, no doubt, a very small 
inertia, can acquire a very high speed under the influ- 
ence of very minute forces; but for the « particles, 
whose dimensions would appear to be identical with 
that of the hydrogen atom, a velocity of 30,000 kilo- 
metres per second seems to be very difficult to explain, 
and I think that, on this point, the experiments of 
Rutherford and his pupils should be taken up anew.^ 

It is hardly to be supposed, moreover, that these 

^ The phosphorescent sulphide is spread in a layer, so thin as to be 
transparent, on a strip of glass first covered with varnish. The side 
coated with phosphorescent matter Is then placed on the substance it is 
desired to examine, and the other face of the glass is observed through 
a magnifying-glass. All uranium and thorium minerals, and even an 
ordinary incandescent mantle, give out a luminescent scintillation indi- 
cating a dissociation of matter; but, in osder to see this, it is necessary 
that the eye be rendered sensitive by previously remaining in the dark 
for a quarter of an hour. 

^ It seems possible that this high speed can be explained by suppos- 
ing that, although the a particles are being constantly emitted, it is 
only when they reach a certain velocity that their existence can be 
recognized by us. Thus, the Hon. R. J. Strutt, in reviewing Professor 
Rutherford's Radio- Activity (2nd ed. ), says: *' Ordinary matter may 
be emitting as many or more a particles than uranium, if only their 
velocity is less than that minimum velocity which has been found 
necessary to produce the characteristic phenomenon." {Nature^ 25th 
January 1906.) — F. L. 


velocities are produced instantaneously; they are 
only comprehensible on the hypothesis that the 
particles of atoms can be compared to small plane- 
tary systems animated with enormous velocities. 
They would preserve their speed on leaving their 
orbits as does a stone launched from a sling. The 
invisible speed of rotation of the elements of the 
atom would therefore be simply transformed into a 
speed of projection visible or in any case perceptible 
by our instruments. 

§ 3. The p Rays or Negative Electrons, 

li rays are considered to be composed of electrons 
identical with those of the cathode rays. They 
should, therefore, be formed of negative electric 
atoms, freed from all matter. Their mass should be, 
like that of the cathode particles, the thousandth 
part of that of the hydrogen atom. Their velocity 
should vary between 33% and 96% of that of light. 

They are emitted in a much smaller proportion 
than that of the a particles, since they hardly form 
1% of the total radiation. It is these rays which 
produce photographic impressions. 

Their penetrating power is considerable. While 
the a rays are arrested by a sheet of ordinary paper, 
the P rays will traverse several millimetres of alu- 
minium. It is probably by reason of their great 
speed that they are much more penetrating than the 
cathode rays of a Crookes' tube, which can only pass 
through sheets of aluminium of a thickness of some 
thousandths of a millimetre. 

They immediately render luminous by impact 
bodies capable of phosphorescence, even when 


separated from them by a thin plate of aluminium. 
The phosphorescence is very bright in platino- 
cyanide of barium and those kind of diamonds — 
rather rare, by-the-by — which are capable of phos- 

The P particles seem to be somewhat complex, as is 
proved by the different speeds of their composing 
elements. This inequality of speed is easily recog- 
nized by the extent of the photographic impression 
they produce when submitted to the action of a 
magnetic field.^ It is likewise noticed, by cover- 
ing the photographic plate with screens of varying 
thicknesses, that different « and P particles pos- 
sess different powers of penetration.^ It is there- 
fore very probable that they represent well marked 

^ It is this very property which I have taken as a basis for the measure- 
ment of the intensity of the various samples of radium I have had occasion 
to examine. When the tube containing a salt of radium renders a 
diamond phosphorescent through a thin strip of aluminium, this salt 
may be regarded as very active. Brazilian diamonds alone — Cape 
diamonds never — are utilizable for this experiment. The first, in fact, 
are capable of phosphorescence by light and the second are not so. I 
have proved this by experiments extending to many hundreds of 
samples, details of which arc given in my memoir on phosphor- 

' Professor J. J. Thomson has also shown this by a very elaborate 
series of experiments, which he sums up by saying that •* the radio- 
active substances, Radium and Polonium, emit when cold slowly- 
moving negatively electrified corpuscles." Later, he has shown that 
this property is possessed by the alkali-metals, and thinks that "with 
more delicate apparatus ... it is probable that this property might be 
delected in all substances." (See Phii. Ma^. for November 1905, 
p. 587.)-F.L. 

' This fact, which was asserted some time since by Professor Ruther- 
ford {PhiL Mag. for May 1904), was for a long lime denied by M. 
Henri Becquerel. Later experiments have, however, convinced him 
that Professor Rutherford is right. (See Comptes Renins de VAca Untie 
des Sciences ^ I2ih February 1906. )—F. L. 


stages of the dissociation of matter .which we are not 
at present able to distinguish. 


§ 4. The y or X rays. 

Together with the o and P rays, the ifirst charged 
with positive, and the second with negative elec- 
tricity, radio-active bodies emit an extremely slight 
proportion (less than one per cent.) of y rays, entirely 
analogous, as to their properties, to the X rays, but 
possessing a higher power of penetration, since they 
can traverse several centimetres of steel. This 
property enables them to .be easily distinguished 
from the a and P rays, which are stopped by a lead 
plate a few millimetres thick. Their nature is other- 
wise but little known, and if they are said to be 
analogous to the X rays, it is solely because they are 
not deviated by a magnetic field and possess great 
penetrating power. 

What complicates to a singular degree the study 
of the above emissions (a, fS and 7) is that none of 
them can touch a gaseous or a solid body without 
immediately causing — no doubt through the dis- 
turbance produced by their enormous velocity — a 
dissociation resulting in the production of rays called 
secondary, which are similar in their properties to the 
primary rays, but less intense. These secondary 
radiations also impress photographic plates, render 
the air a conductor of electricity, and are deviated by 
a magnetic field. They are able to produce, by their 
impact, tertiary rays having the same properties and 
so on. It is the secondary rays produced by the 
y rays which are the most active. A photographic 
impression through a metallic plate is sometimes 


intensified by the interposition of that plate, because 
the action of the secondary rays is then superposed 
on that of the primary rays. 

§ 5. Semi-material Emanation proceeding from the 

Radio-active Substances. 

One of the most curious properties of the radio- 
active, and, moreover, of all substances, is that of 
incessantly emitting a non-electrified product, desig- 
nated by Rutherford as the emanation. This emana- 
tion represents the first stages of the dissociation 
of matter, and, by its disaggregation, generates 
emissions of the particles studied in the preceding 
paragraph. To this emanation is also due the 
property possessed by radium of rendering radio^ 
active all bodies placed in its neighbourhood. 

The emanation has been especially studied in the 
case of radium and of thorium. Uranium does not 
give enough of it to be revealed by reagents. It is, 
however, very probable that, contrary to the opinion 
of Rutherford, it does disengage an emanation, since, 
according to the researches of J. J. Thomson, the 
majority of bodies in nature, water, sand, etc., produce 
one also. 

The emanation can be drawn from any radio-active 
bodies, either by dissolving them in any liquid placed 
in a receiver communicating with a closed tube, or by 
bringing them to a red heat in a similar apparatus. 
The emanation drawn into the tube renders it phos- 
phorescent by its presence, which fact allows of its 
behaviour being examined. It can be condensed by 
the cold produced by liquid air. This condensa- 
tion is revealed by the localization of the phos- 


phorescence, but no substance capable of being 
measured by the balance appears. As the emanation 
of thorium condenses at 120° C, and that of radium 
at 150° C, it seems very likely that the emanations of 
different bodies, some resemblances notwithstanding, 
display various properties. 

At the ordinary temperature radio-active bodies 
in a solid state emit the emanation, but only a 
hundredth part of the quantity emitted in the state 
of solution. By introducing sulphide of zinc into a 
bulb containing a solution of chloride of radium, 
the disengagement of the emanation renders the sul- 
phide phosphorescent. Radium, when heated, loses 
the greater part of its activity by reason of the 
quantity of emanation it gives off, but it regains it 
entirely in twenty days or so. The same loss occurs 
when a solution of this salt is heated to boiling. 

When solid chloride of radium has been brought 
to a red. heat, or a solution of it has been boiled for 
some time, it still preserves a quarter of its primary 
activity, but this latter is then solely due to the a 
particles, as can be noted by the weak penetrating 
power of the rays emitted, which can no longer 
pass through a sheet of paper. It is only after a 
certain lapse of time that the appearance of the P 
rays, capable of passing through metals, again 
takes place. The activity of the emanation is lost 
rather quickly. The rapidity of this loss varies 
according to the substance. That of actinium is 
destroyed in a few seconds, that of thorium in a 
few minutes, that of radium only at the end of 
three weeks, but it is already reduced by one-half 
in four days. 

According to Rutherford, radium and thorium 


produce different kinds of emanations, that is, of dis- 
sociations which begin with the emission of the 
emanations. He has already counted five or six 
belonging to this last. The first engenders the 
second, and so on. They no doubt represent succes- 
sive stages of the dematerialization of matter. 

To the emanation are due three-fourths of the 
heat incessantly produced by radium, which main- 
tains its temperature at 3** or 4**C. above the ambient 
medium. If, in fact, radium be deprived of its 
emanation by heating, it gives out no more than a 
quarter of the heat it emitted at first. Almost all 
the rise in temperature is due to the a particles. 

It results, as I have already remarked, from the 
experiments of Ramsay, that if some emanation of 
radium is left for some days in a tube, there can 
be observed the spectral lines of helium which were 
not there in the first instance. 

Before drawing too many conclusions from this 
transformation, it must be first remarked that helium 
is a gas which accompanies all radio-active minerals. * 
It was even from these bodies that it was first 
obtained. This gas enters into no chemical com- 
bination,* while it is the only substance hitherto 
found impossible to liquefy and can be kept for an 
indefinite time in the tubes in which it is enclosed. 
. This derivative of radium must be a very special 
helium since it appears to possess the property of 
spontaneously vanishing. Its sole resemblance to 
ordinary helium would seem to consist in the 
momentary presence of some spectral rays. It 

^ This can now hardly be said. Dr. Ternent Cooke has shown that 
helium in certain circumstances forms an unstable compound with 
cadmium. (See Proc, Roy. Soc, 8th February 1906.) — F. L. 


therefore seems very difficult to admit the transforma- 
tion of radium into helium. 

Rutherford considers the emanation as a material 
gas, because it can be diffused and condensed in the 
manner of gases. No doubt the emanation has some 
properties in common with material bodies, but does 
it not curiously differ from these last by its property 
of vanishing in a few days, even when enclosed in 
a sealed tube, by transforming itself into electric 
particles ? Here, especially, is shown the utility of 
the notion we have endeavoured to establish, of an 
intermediary between the material and the im- 
material — that is to say, between matter and the 

The emanation of the radio-active bodies re- 
presents, according to me, one of these intermediate 
substances. It is partly material, since it can be 
condensed and dissolved in certain acids and re- 
covered by evaporation. But it is only incompletely 
material, since it ends by entirely disappearing 
and transforming itself into electric particles. This 
transformation, which takes place even in a sealed 
glass tube, has been proved by the experiments 
of Rutherford. He has shown that in disappearing 
the emanation at first gives birth to a particles and 
only later to P particles and y radiations. 

To prove that the emanation of radium or of 
thorium only generate at first positive or a particles, 
it is placed in a brass cylinder .05 mm. thick, which 
retains all the a particles, but allows the P particles 
and 7 rays to pass through. By noting at regular 
intervals by means of an electroscope the external 
radiation of the cylinder, it can be seen that it is only 
at the end of three or four hours that the P particles 


appear. The a particles, on the contrary, show 
themselves at once, as is proved by their action on 
an electroscope connected with the interior of the 

Rutherford concludes from his experiments that 
"the emanation" at ifirst emits only « rays, then 
P and y rays by deposition on the walls of the con- 
taining cylinder. It is difficult to conceive, from 
all we know of electricity, an emission of solely 
positive particles without a similar negative charge 
being produced at the same time. 

However that may be, if the above theory be 
correct, the emanation in disappearing first produces 
positive ions relatively voluminous, then negative 
electrons, a thousand times less so, and finally y 

Rutherford considers the emanation to be a sort of 
gas capable of spontaneously dissociating into elec- 
tric particles expelled with immense velocity. In 
the course of dissociation this supposed gas would 
emit three million times the amount of energy pro- 
duced by the explosion of an equal volume of 
hydrogen and oxygen mixed in the proportions 
required for the formation of water. This last re- 
action is, however, as is well known, that which pro- 
duces most heat. 

Is this emanation, which produces so large a 
quantity of electric particles, itself electrified ? 
In no way. Rutherford asserts this positively, but 
this important point has been very clearly demon- 
strated by the researches of Professor MacClelland. 
" The fact," he says, " that the emanation is not 
charged has an important significance from the 
point of view of our conception of the manner in 


which the radium atom destroys itself. The radium 
atom assuredly produces a particles charged 
positively. But the particles of the emanation 
cannot be what remains of the atom after the 
emission of the a particles, for, in that case, 
they would be charged negatively." There results 
from these experiments and the observations pre- 
viously made by me that everything relating to the 
a particles, which form 99% of the emission of radio- 
active bodies, requires to be entirely re-examined. 

§ 6. Induced Radio-activity. 

It is the emanation which, by freeing itself and 
by projecting its disaggregated particles on to the 
surface of other bodies, produces the so-called induced 
radio-activity. This phenomenon consists in all 
substances placed in the neighbourhood of a radio- 
active compound becoming momentarily radio-active. 
They do not become so if the active salt is enclosed 
in a glass tube. . The /? and y rays are alone capable 
of producing induced radio-activity. The a particles 
do not seem to possess this power. Radio-activity, 
artificially provoked in any substance, disappears 
only after a fairly long time. 

All gases or metals placed close to a radio-active 
substance or on which is blown, by means of a long 
tube, the emanation which it disengages, become 
momentarily radio-active. If it be admitted that 
this radio-activity is generated by the freeing of 
electric particles, it must be supposed that these 
particles are capable of being carried along by the 
air and of attaching themselves like, dust to other 
bodies, and possess properties singularly different from 


those of ordinary electricity. Rutherford has verified 
the fact that the emanations of thorium can pass 
through water and sulphuric acid without losing their 
activity. If a metallic wire charged with negative 
electricity be exposed to the emanations of thorium, 
it becomes radio-active ; if this wire be treated with 
sulphuric acid and the residuum then evaporated, it 
will be found that this latter is still radio-active. 
One really does not see how electricity could bear 
such treatment. 

The induced radio-activity communicated to an in- 
active substance may be mucti more intense than that 
of the radio-active substance from which it emanates. 
When, in an enclosed vessel, containing some 
emanation from a radio-active body — thorium, for 
example — a metal plate charged with negative 
electricity at a high potential is introduced, all the 
particles emitted by the thorium concentrate them- 
selves upon it, and, according to Rutherford, this plate 
becomes ten thousand times more active, surface for 
surface, than the thorium itself. These facts are 
not, any more than the preceding ones, explicable 
by the current theory. 

If a metal, rendered artificially radio-active, be 
brought to a white heat, it loses its radio-activity, 
which spreads itself over the bodies in its neighbour- 
hood. Here, again, we see the so-called electric 
atoms behave in a very strange manner. 

The phenomenon of induced radio-activity is, 
then, quite inexplicable with the current ideas as 
to electric particles. It cannot be admitted that 
such particles deposited on a metal can remain for 
weeks in the state of electric atoms and be carried 
along by reagents. It would seem, from M. Curie's 


experiments, that bismuth, plunged into a solution 
of bromide of radium and carefully washed immedi- 
ately, remains radio-active for at least three years. 
This radio-activity would even seem to persist after 
energetic chemical treatment. Can it be considered 
likely that electric particles act in such a- manner ? 
And, since they act so differently from electricity, 
how is it possible, as I have so often repeated, 
to persist in applying to them the term "electric** 
atoms ? 

I must remark with respect to induced radio- 
activity, that certain forms of energy can be stored 
in bodies for a great length of time and expend them- 
selves very slowly. In my former experiments on 
phosphorescence I noted that sulphide of calcium, 
exposed to the^sun for a few seconds, radiates in- 
visible light for eighteen months, as is proved by the 
possibility of photographing the insolated object in 
the dark room or in the most complete darkness. 
At the end of eighteen months it no longer gives any 
radiation, but still preserves a residual charge which 
persists for an indefinite period, and can be made 
visible by causing invisible infra-red rays to fall on 
the surface of tfce insolated body. 

A radio-active body has been compared to a 
magnet which keeps its magnetism for ever, and 
can, without losing its power, magnetize other 
bodies. There is little foundation for this com- 
parison, for the magnet is not the seat of a constant 
emission of particles into space.^ It might, however, 

^ M. Villard's experiments, however, have given him some reason 
to think that an electro- magnet may, under certain conditions, actually 
emit particles of magnetism which he calls " magnetons." (See Revus 
GeniraU des Sciences ^ 15th May 1905.) — F. L. 



be employed to explain roughly the phenomenon of 
induceif radio-activity, which could be reduced 
to the fact that a radio-active body imparts its 
properties to a neighbouring body, as the loadstone 
gives magnetization to fragments of iron near it. 
If the molecules of the air were magnetic — and they 
are so in a slight degree — a loadstone would magnetize 
them, and they themselves might magnetize others. 
If they preserved their magnetism, we should have a 
gas, which, like the emanation of radio-active bodies, 
would be able to circulate in tubes and remain 
persistently on the surface of a metal without losing 
its properties. 

From all that has been set forth above one general 
consideration emerges, and this confirms what has 
been said at the commencement of this chapter — 
namely, that the stages of the dissociation of matter 
must be extremely numerous and that but few of 
them are yet known to us. Without being able to 
isolate them, we are, at least, certain that they exist, 
since the unequal deviation of the P particles by a 
msLgnet proves clearly that these are composed of 
different elements. We equally know that, in the 
semi-material product designated uftder the general 
name of emanation, already four or five very different 
stages of the dissociation of matter may be noted. 

The same experiments equally confirm this other 
view — that matter, in dissociating, emits products, 
more and more subtle, more and more dematerialized, 
which progressively lead to the ether. The positive 
ion is still largely charged with matter. The 
negative electrons are nearer to the ether. They 
themselves represent varied stages of dissociation, 
since their unequal deviation by the same magnetic 


jfield proves that they are composed of different 
elements. Finally, we come to the 7 radiations, 
which are no longer stayed by any obstacle, which 
no magnetic attraction can deviate, and which seem 
to constitute one of the last phases of the dissociation 
of matter before its final return to the ether. 



§ I. Divers Causes of the Dematerialization of Matter. 

Methods employed to verify it 

Many years have elapsed since I proved that the 
dissociation of matter observed in the substances 
called radio-active, such as uranium and radium, 
was, contrary to the ideas then accepted, a property 
belonging to all bodies in nature, and capable, of 
manifesting itself under the influence of the most 
varied causes and even spontaneously. The spon- 
taneous radio-activity of certain substances, such as 
uranium and thorium, which has so taken physicists 
by surprise, is in reality a universal phenomenon and 
a fundamental property of matter. 

In a recent study,^ Professor J. J. Thomson has 
again taken up this question, and has succeeded in 
showing the existence of radio-activity in most bodies 
— water, sand, clay, brick, etc. He has drawn from 
them an "emanation" which is produced in a continu- 
ous manner, similar to that extracted by Rutherford 
from radium and having the same properties of 

^ On the Presence of Radio-active Matter in Ordinary Substances 
{Proceedings of Ike Cambridge Philosophical Society, April 1904, p. 


2 It should be noted that in the memoir referred to, Professor J. J. 
Thomson mentions that the ** capriciousness " of the emanations 
obtained indicates " that they are due to minute traces of a radio-active 



These experiments confirm all those I had already 
published on the spontaneous dissociation of matter, 
but they in no way prove, as Elster and Geitel would 
believe, that there is radium everywhere.^ It was the 
only explanation to which the last partisans of the 
indestructibility of matter could attach themselves. 
To admit that the atoms of two or three exceptional 
bodies can be dissociated is less embarrassing than to 
acknowledge that there is here a question of an abso- 
lutely general phenomenon. 

My experiments, moreover, take away all verisimi- 
litude from such explanations. When we succeed 
in varying enormously the radio-activity of a body by 
certain chemical reactions, when we render greatly 
radio-active, by admixture, substances such as tin 
and mercury, which apart are not so, is it really 
possible to imagine that radium can have anything 
to do with the radio-activity then observed ? 

impurity." This has not been conHrmed, so far as I am aware, by sub- 
sequent experiments, and it is coupled with the observation that "there 
is, I think, a considerable amount of evidence that most, if not all, 
bodies are continually emitting radiation which, like the Rontgen rays, 
can ionize a gas through which it is passed." M. Blondlot, the well- 
known professor of Nancy, on the other hand, has since made experi- 
ments that go to show that an emanation capable of increasing the light 
of a phosphorescent screen, which can be deviated by a magnetic or 
electric field or a draught of air, is emitted at ordinary temperatures by 
copper, silver, zinc, damped cardboard, all liquids, odorous substances 
such as camphor and musk, and the human body. (See Comptes 
Rendus <fe PAcad, des Set',, 13th and 27th June, 4th and 25lh July 
1904.) — F. L. 

^ This does not seem to be Professors Elster and Geitel's present 
opinion. Their most recent utterance on the subject is that the 
spontaneous ionization of the atmosphere is due to a very penetrating 
radiation resembling that emitted by uranium and present all over the 
earth's surface. They found it able to penetrate 20 cm. of lead, but 
that it is subject to a larre loss of power in passing through rock-salt. 
{%t^ Physikalische Zeitschrift^ 15th January 1906.) — F. L. 


It was only thanks to long and minute experiments 
that I was able to establish the universality of the 
dissociation of matter. Some of these will be set 
forth in the second part of this work. Here only a 
summary of the results obtained will be given. 

What phenomena now can be relied upon for the 
demonstration of the dissociation of ordinary 
matter? Exactly those which prove the dissociation 
of the particularly radio-active substances, such as 
radium and thorium — that is to say, the production 
of particles emitted at an immense speed, capable of 
rendering the air a conductor of electricity and of 
being deviated by a magnetic field. 

There exist other accessory characteristics: photo- 
graphic impressions, production of phosphorescence 
and fluorescence, etc., by the emitted particles, but 
they are of secondary importance. Besides which, 
99 per cent, of the emission of radium is composed of 
particles having no action on photographic plates, 
and there exist radio-active substances such as 
polonium which only emit rays such as these.^ 

The most important among the characteristics 
above enumerated is the emission of particles able to 
render the air a conductor of electricity and conse- 
quently capable of discharging an electroscope at a 
distance. It has been exclusively made use of in 
the separation of radium. It is therefore the one to 
which we shall principally have recourse. 

The possibility of deviating these particles by a 
magnetic field constitutes the next most characteristic 

^ Since this was written, successful attempts have been made to 
impress a photographic plate with the j3 rays from polonium or, what is 
the same thing, radio-telUirium. Cf. Prot. Roy. Soc.y 2ist July 1906 
(Professor Huffs experiments). — F. L. 


phenomenon. It has permitted the identity of the 
particles emitted by substances endowed with radio- 
activity, whether spontaneous or excited, with the 
cathode rays of Crookes* tubes to be indisputably 
established. It is the degree of deviation of these 
particles by a magnetic field which has enabled their 
speed to be measured. 

§ 2. Dissociation of Matter by Light. 

It was by attentively studying the action of light 
on metals and noting the analogy of the effluves 
emitted with the cathode rays that I was led to the 
discovery of the universality of the dissociation of 

It will be seen in the experimental part of this 
work that the technique of the experiments demon- 
strating the dissociation of bodies under the influence 
of light is pretty simple, since it amounts to throwing 
on to a positively charged electroscope the effluves of 
dissociated matter emitted by a metallic plate struck 
by light. These effluves are not produced by metals 
alone, but by the majority of substances. In some, 
the emission, surface for surface, may be forty times 
more considerable than that produced by certain 
spontaneously radio - active substances, such as 
thorium and uranium. 

For a long time the composition of these effluves 
which I asserted to be of the nature of cathode rays, 
and of the radiations emitted by radio-active bodies, 
was contested, but at the present day no physicist 
denies this identity. 


The effluves produced under the action of Hght, 
like the cathode rays, render the air a conductor of 
electricity, and they are also deviated by a magnet. 
The electric charge of these component particles, as 
measured by J. J. Thomson, has been found equal to 
that of the cathode particles. 

I shall show in the experimental part of this work 
that the different parts of the spectrum possess very 
different powers of dissociation, and that the resist- 
ance of various bodies to dissociation by light is very 
unequal. The ultra-violet is the most active region. 
In the extreme regions of the ultra-violet produced 
by electric sparks — regions which do not exist in 
the solar spectrum, because they are absorbed by 
the atmosphere, — it may be noted that all bodies 
dissociate with far greater rapidity than in ordinary 
light. In this part of the spectrum, substances 
which, like gold and steel, are not sensibly affected 
by solar lights emit effluves in quantities sufficiently 
abundant to discharge the electroscope almost 
instantaneously. If the earth were not protected 
from the extreme solar ultra-violet rays by its 
atmosphere, life on its surface, under existing cir- 
cumstances, would probably be impossible. 

Solar light does not possess the property of 
dissociating the molecules of gases. These can 
only be dissociated by the absolutely extreme ultra- 
violet radiations. If, as is probable, these radia- 
tions exist in the solar spectrum before their 
absorption by the atmospheric envelope, an energetic 
dissociation of the aerial gases must take place 
on the confines of our air. This cause must have 
contributed, in the course of ages, to deprive certain 
stars, like the moon, of their atmosphere. 


§ 3. Dissociation of Matter by Chemical Reactions. 

We now arrive at one of the most curious and 
unexpected parts of my researches. Convinced of 
the general character of the phenomena I had noted, 
I asked myself whether chemical reactions might not 
generate effluves similar to those produced from sub- 
stances by light, and which would still possess the 
common characteristic of dissipating electric charges. 
Experiment has fully confirmed this hypothesis. 

Here was a fact .hitherto absolutely unsuspected. 
It had long been known, since the observation goes 
back as far as Laplace and Lavoisier, that hydrogen, 
prepared by the action of iron on sulphuric acid, was 
electrified. This fact ought to have impressed physi- 
cists the more that the direct electrification of a 
gas is impossible. A gas left for an indefinite period 
in contact with a metallic plate charged with 
electricity never becomes electrified. If the air 
could be electrified it would no longer be an insu- 
lator, an electroscope could no longer keep its charge, 
and the majority of electrical phenomena would still 
be unknown to us. But this fact, so important, since 
it contained the proof, then concealed, that matter 
is not indestructible, remained totally unnoticed. 

The most striking phenomena hardly attract our 
attention except when light is thrown upon them by 
other phenomena, or when some great generalization 
capable of explaining them forces us to examine 
them more closely. If, in Lavoisier's experiments 
just alluded to, hydrogen was found to be electrified, 
it was only because the atoms of this substance had 
undergone the commencement of dissociation. It is 


curious to note that the first experiment from which 
it could be deduced that matter is perishable had for 
its author the illustrious savant whose greatest claim 
to glory is that of endeavouring to prove that matter 
is indestructible. 

The experiments collected at the end of this work 
prove that a large number of chemical reactions, 
whether accompanied or unaccompanied by the 
disengagement of gas, produce effluves similar to the 
cathode rays, and therefore reveal a destruction of 
matter without return during the reactions. 

Among these reactions I shall only mention : the 
decomposition of water by zinc and sulphuric acid or 
merely by the sodium amalgam, the formation of 
acetylene by carbide of calcium, the formation of 
oxygen by the decomposition of oxygenated water by 
means of dioxide of manganese, and the hydration 
of sulphate of quinine. 

As regards sulphate of quinine, it presents highly 
curious phenomena. This body, as it has long been 
known, becomes phosphorescent by the action of 
heat, but what was not known is that after having 
lost its phosphorescence, if sufficiently heated it 
becomes highly luminous and radio-active on re- 
frigeration. After seeking the cause of its phos- 
phorescence on cooling, and proving it to be due to a 
very slight hydration, I noted that by reason of this 
hydration the substance became radio-active for a 
few minutes. It was the first instance I discovered 
of the dissociation of matter — that is to say, of radio- 
activity — by chemical reactions, and it led me to 
the discovery of many more. 

Since then, Dr. Kalahne, Professor of Physics at 
the University of Heidelberg, has taken up again the 


same subject in an important study. " My observa- 
tions," he says, "absolutely confirm that the chemical 
phenomena pointed out vby Gustave Le Bon is the 
cause of the radiation."^ 

Rutherford also had my results relating to sulphate 
of quinine verified by one of his pupils, who devoted 
a paper to the subject.^ This work was skilfully 
performed, and published in the Physical Review. 
Rutherford has adopted and reproduced the con^ 
elusions in his great work on radio-activity.^ 

The author has noted, as I did, that the air became 
a conductor of electricity, and that the phenomenon 
was duly produced, as I had said, by the hydration 
of sulphate of quinine, but he thinks that the 
radio-activity is due to a chemical reaction or "to 
a kind of ultra-violet light," generated by the phos- 

That the radio-activity was due to chemical 
reaction is exactly what I wished to demonstrate, 
and this Professor Kalahne has confirmed; that 
it was due to ultra-violet light is impossible,* for the 
reason that the phosphorescence persists longer than 
the radio-activity, a thing which would not happen if 

^ Ann, der Physik, 1905, p. 450. " This memoir," says the author 
at the outset, ** contains the results of my researches on the radiation of 
sulphate of quinine as discovered by Gustave Le Bon." The same 
subject had been previously examined by a dilTerent method by Miss 

2 Miss Gates, {^te Physical Review, vohy^viW. — 1904 — p. 144.) She 
came to the conclusion that while Dr. Le Bon is right as to the cause of 
the radiations, they differ from those of the radio-active substances in 
several particulars. But see Kalahne, Ann, der Physik, iQOSi P* 457- 
— F. L. 

3 Radio- Activity ^ 1st ed., p. 9. 

* This Miss Gates has since admitted. (See Physical Revie^v, 1906, 
p. 46.) — F. L. 


the latter were the consequence of the light produced 
l?y the phosphorescence. 

Rutherford thinks that the radiations thus pro- 
duced differ from those of the radio-active substances 
because, he says, they have little penetrating power. 
He is not unaware, however, that this penetration 
proves nothing, since, according to him, 99 per cent, of 
the emission of radium is stopped by a thin sheet of 
paper, and certain very radio-active substances, such 
as polonium, only emit radiations having no penetra- 
tion.^ I think that in writing the above the eminent 
physicist was still under the influence of the idea, 
very widespread at the outset, that radio-activity 
was the exclusive appanage of a small number of 
exceptional bodies. 

^ 4. Dissociation of Matter by Electric Action. 

Certain very intense electric actions — for instance, 
induction sparks fifty centimetres long between which 
is placed the body to be experimented on — do exercise 
a slight action — that is to say, render the bodies sub- 
mitted to their influence slightly radio-active; but 
the effect is much weaker than that produced by a 
simple ray of light or by heat. 

This is not very astonishing. Electricity, as I 
shall show farther on, is a product of the dissociation 
of matter. It can certainly generate, like the 
cathode rays or radio-active emissions, secondary 
radiations in the substances struck by it, but the ipns 

^ The last experiments go to show that polonium emits j8 rays which 
are as penetrating as those of radium. Cf. Professor Giesel in Berichtey . 
1906 (Bd. xxxix.), p. 780. They lack confirmation, but are probably 
correct.— F. L. 


to which it gives birth in the air have too low a 
speed to produce much effect. 

No doubt it is known, from the experiments of 
Elster and Geitel, that a wire electrified to a high 
potential acquires a temporary radio*activity; but it 
may be supposed in that case that the wire, by 
reason of its electrification, only attracts the ions 
which are always present in the atmosphere. 

It was by pursuing the study of radio-activity 
excited by electricity that I was led to effect the 
experiment which will be mentioned later, and to 
compel particles of dissociated .matter to traverse, 
visibly, and without deviation, thin plates of glass 
or ebonite. 

§ 5. Dissociation of Matter by Combustion. 

If slight chemical reactions, such as simple hydra- 
tion, can provoke the dissociation of matter, it will 
be conceived that the phenomena of combustion, 
which constitute powerful chemical reactions, must 
realize the maximum of dissociation. This is, in 
fact, what is observed. A burning body is an in- 
tense source of cathode rays similar to those emitted 
by a radio-active body, but possessing, by reason 
of their low speed, no great penetration. 

For at least a century it has been known that the 
gases arising from flames discharge electrified bodies. 
Branly has shown that, even when cooled, gases 
preserve this property. All these facts remained 
uninterpreted, and it was hardly suspected that 
within them dwelt one of the proofs of the dissocia- 
tion of matter. 

This was, however, a conclusion to which one was 


bound to come. It has been clearly confirmed by 
the recent researches of J. J. Thomson. He has 
shown that a simple metal wire or thread of carbon 
• brought to a white heat — the carbon thread of an 
incandescent lamp, for example — is a powerful and 
almost unlimited source of electrons and ions — that 
is to say, of particles identical with those of radio- 
active bodies. He has proved it by showing that 
the relation of their charge to their mass was the 
same. "We are therefore brought to this con- 
clusion," he says, " that from an incandescent metal 
or a heated thread of carbon electrons are projected." 
Their quantity is enormous, he points out; for the 
quantity of electricity which these particles can 
neutralize corresponds to many amperes per square 
centimetre of surface. No radio-active body could 
produce electrons in such proportion. If it be con- 
sidered that the solar spectrum indicates the presence 
of much carbon in its photosphere, it follows that 
the sun must emit an enormous mass of electrons, 
which, on striking the upper layers of our atmo- 
sphere, perhaps produce the aurora borealis through 
their property of rendering rarefied gases phosphor- 
escent. This observation squares perfectly with my 
theory of the maintenance of the sun's heat by the 
dissociation of the matter of which it is composed. 

§ 6. Dissociation of Matter by Heat. 

Heat much inferior to that produced by combustion 
— that is to say, not exceeding 300° C. — is sufficient 
to provoke the dissociation of matter. But in this 
case the phenomenon is rather complicated, and its 
explanation has required very lengthy researches. 


The reason is that, in reality, heat does not in this 
case appear to act directly as the agent of dissociation. 
I shall show in the chapter devoted to my experi- 
ments that it acts as if the metal contained a limited 
provision of a substance similar to the emanation 
of radio-active matter, which it gives out under 
the influence of heat, and then only recuperates 
by repose. It is for this reason that, after a metal 
has been rendered radio-active by a slight heat, it 
soon loses all trace of radio-activity, and regain? 
it only after several days. It is, too, in this way 
that radio-active substances really behave, but in 
consequence of their activity being much superior 
to that of ordinary substances, whatever they lose 
from time to time is again formed simultaneously, 
unless they are brought to a red heat. In this last 
case the loss is only made up after a certain lapse of 

When I published these experiments, J. J. Thom- 
son had not yet made known his researches which 
proved that nearly all substances contain an emana- 
tion^ comparable with that of radio-active: bodies, 
such as radium and thorium. His observations fully 
confirm my own. 

§ 7. Spontaneous Dissociation oj Matter. 

The experiments alluded to above prove that most 
substances contain a provision of radio-active matter 
which can be expelled by a slight heat and spon- 
taneously formed anew; these substances are there- 
fore, like ordinary radio-active substances, subject to 

^ See note on p. 148.— F. L. 


spontaneous dissociation. It is, however, extremely 

In the foregoing experiments this spontaneous 
dissociation has only been made evident by means 
of slight heat. It is possible, however, by the help 
of various artifices — for instance, by folding the 
metal over itself so as to form a closed cylinder — 
to allow radio-active products to form therein, the 
presence of which is verified by the electroscope. 
The substance thus experimented on, however, soon 
ceases to be active. It has not on that account used 
up all its provision of radio-activity; it has simply lost 
all that it can emit at the temperature under which 
the operation is effected. But, as with phosphor- 
escent substances or radio-active matter, it suffices 
to heat it a little for it to produce an increased 
quantity of active effluves. 

The researches I have just summarized prove that 
all substances in nature are radio-active, and that 
this radio-activity is in no way a property peculiar to 
a few bodies. All matter, then, tends spontaneously 
towards dissociation. This latter is most often 
very small, because it is hindered by the action of 
antagonistic forces. It is only exceptionally, and 
under different influences, such as light, combustion, 
chemical reaction, etc., capable of striving against 
these forces, that dissociation reaches a certain 

Having proved by the experiments just summar- 
ized, of which the details will be found at the end of 
this volume, that the dissociation of matter is a 
general phenomenon, I am entitled to say that the 
doctrine of the invariability of the weight of atoms, 
on which all modern chemistry is based, is only an 


illusion resulting entirely from lack of sensitiveness 
in our balances. Were they sufficiently sensitive, all 
our chemical laws would be considered as merelv 
approximations. With exact instruments we should 
note in many circumstances, and particularly in 
chemical reactions, that the atom loses a part of 
its weight. I may, then, be allowed to affirm that, 
contrary to the principle laid down as the basis of 
chemistry by Lavoisier, we do not recover in a chemical 
combination the total weight of the substances employed 
to bring about this combination. 

§ 8. The Part taken by the Dissociation of Matter in 

Natural Phenomena. 

We have just seen that very different causes acting 
in a continuous manner, such as light, can dissociate 
matter and finally transform it into elements which 
no longer possess any material properties, and cannot 
again become matter. 

This dissociation, which has gone on since the 
beginning of the ages, must have played a great part 
in natural phenomena. It is probably the origin of 
atmospheric electricity, and no doubt that of the 
clouds, and consequently of the rainfall which exer- 
cises so great an influence on climate. One of the 
characteristic properties of radio-active emissions is 
that of condensing the vapour of water, a property 
which also belongs to all kinds of dust, and is 
demonstrated by an experiment of long standing.^ 
A globe full of water in ebullition is placed in com- 

^ See, for further details, Mr. John Aitken on **Dust, Fog, and 
Clouds*' {Trans. Roy. Soc, £din.,vo\. xxx. (1883) pp. 337 ef seg.). Cf. 
C. T. R.Wilson on ''Condensation Nuclei," Phii. Trans, ^ vol. cxcii. 
pp. 403 et seq.). — F. L. 



munication with two other globes, one filled with 
ordinary air from a room, the other filled with the 
same air cleared of dust by simple filtration through 
cotton-wool. It can then be seen that the steam 
coming into the globe containing the unfiltered air 
immediately condenses into a thick fog, while that in 
the globe containing pure air does not condense. 

We see how the importance of the phenomenon of 
the dissociation of matter increases with the study of 
it. Its universality spreads daily, and the hour is not 
far distant, I believe, when it will be considered as 
the source of a great number of the phenomena 
observed on the surface of our planet. 

But these are not the most important of the 
phenomena due to the dissociation of matter. We 
have already shown it to be the source of solar 
heat, and we shall see presently that it is the origin 
of electricity. 


We shall see in a later chapter that the particles 
which escape from an electrified 
point connected with one of the 
poles of an electrical machine in 
motion are composed of ions and 
electrons of the same composition as 
the particles of dissociated matter 
emitted by .the radio-active sub- 
Stances or by a Crookes tube. p,^,i^,„ „, j;^. 
They, too, render the air a conductor dated matter not 
of electricity, and are deviated by subjeciedioaiirac- 
a magnetic field. If, therefore, we """for repolaons. 
. , , I ..■1 ■ I- 1 ■ 1 — [/mlaHtaneaus 

Wish to study the equilibria 01 which photosraph.'\ 
the elements of dissociated matter 
are capable, we may replace a radio-active body 
by a point electrified by being connected with 
of the poles of an 
electrical machine in 
I action. 
Fic. s.-A.tractioi:s of particles . ^hese particles are sub- 

of dissociated mailer chained ject to the laws of attrac- 

wilh position and negaiive tions and repulsions which 

declricity - \InUanlan,,u: ^^^^^ ^j glgctnc pheno- 

mena. By utilizing these 

laws we can obtain at will the most varied 




Such equilibria can only be maintained for a mo- 
ment. If we were able to isolate and fix them for good 
— that is to say, so that 
they would survive their 
generating cause— we 
should have succeeded in 
creating with immaterial 
particles something singu- 
larly resembling matter. 
The enormous quantity 
of energy condensed with - 
Fig. 6.— Repulsion of pnrlicles of in the atom shows the 
dissocmied mau« emiited by impossibility of realizing 

Iwo poinis and movins in the . . , 

direction of the lines of force.- ^"^^^ ^" expenment. 
[Instantaneous fhiHosvafk.} But, if we Cannot with 

immaterial . things effect 
equilibria able to sur- 
vive the cause which gave 
. them birth, we can at 
least maintain them for a 
sufficiently long time to 
photograph them, and 
thus create a kind of mo- 
mentary materialization. 

By utilizing nothing but 

the laws mentioned above 

Fir,. 7.— Repulsion of particles of I have Succeeded in group- 

, dissociated matter emitted liy ;„„ ^he particles of dis- 

several oam\s.— [liislati/aiieons. ■ . 1 .. 

pho!c,sraph.\ sociated matter, so as to 

give to this grouping every 

possible form — straight and curved lines, prisms, 

cells, etc., which were then made permanent by 


In Figs. 8 to II we see straight and curved 


figures produced by the mutual repulsions of particles 
of dissociated matter having electrical charges of 

Fig. lo. Fig. ii. 

Several figures olilnined by compelling particle^ of dissociated mnlter 
lo move and tepel each other in certain direclions. 

the same sign. So soon as the particles are brought 
near enough to each other, they repel one another 
and do not succeed in touching, as can be seen 
by the dark lines separating them and the consider- 
able shortening of the radiation on the side where 


the particles are. By multiplying the discharges, 
by means of an arrangement of fine needles, the 
regular forms of Figs. 12 to 15 are obtained. 

The polygonal forms, represented in some of the 
photographs, are not, of course, reproductions of 
plane surfaces, but of forms really possessing three 
dimensions, of which photography can only give the 
projection. They are, therefore, really figures in 
space which I have obtained by maintaining for a 
moment in the equilibrium forced upon them par- 
ticles of dissociated matter. 

The particles which form the model of the images 
h§re produced, are not composed entirely of electrons. 
According to current ideas, they should be regarded 
as electric atoms surrounded by a retinue of material 
particles. They are therefore composed of those ions 
which we studied in a former chapter. But the 
nucleus of these latter is constituted of those electric 
atoms which are produced by the dematerialization 
of matter. 

Among the forms of different equilibrium that we 
can cause particles of dissociated matter to assume, 
there is one — the globular form — of which the theory 
has* not yet been established, attraction and repul- 
sion not sufficing for its explanation. It is probable 
that th^e electric atoms must here be in a special 
state of whirling equilibrium. This equilibrium, 
though still momentary, is much more stable than 
those in the preceding experiments. 

Electricity' in this form has more than once been 
observed during storms, but rarely enough for its 
existence to have been long denied. In such cases, 
it occurs in the form of brilliant globes which may 
attain the size of a child's head. They revolve 


slowly, and finally burst with a noise like a shell, 
causing great damage. The energy enclosed in 
them is therefore considerable, and I willingly appeal 
to this example for the comprehension of what may 

Fig- M- Fig. 15. 

Appaitnt maUrialkatlons produced in space by iiiilkhi^ the repulsiam 
of dissocialtd mailer. — In Fig. \z will be seen how repulsions are 
effected between particles issuing from four neighbourine electrified 
points. In Figs. 13, 14, and 15, ihe numlier of points has been 
inulLiplied, and we have succeeded in creating in space the figures 
which are represented in the phott^rapha. Some of these remind 
us, by their forms, of the cells of living beings. 


be done with condensed energy in a state of equili- 
brium of at least momentary stability. 

We cannot hope to generate in our laboratories 
phenomena of such intensity, but we can reproduce 
them on a small scale. Small luminous spheres 
imitating globular thunderbolts^ can be produced by 
various methods. That of M. Stephane Leduc per- 
mits them to be very easily formed. It suffices to 
place on a photographic plate, at a few centimetres 
from each other, two very thin rods connected with 
the different poles of a static machine. There soon 
issues from the rod connected with the negative 
pole small luminous spheres, apparently about one 
millimetre in diameter, which very slowly make for 
the other rod, and vanish as soon as they touch it. 

But, with this mode of operation, one may always 
suppose a particular form of effluve to exist between 
the two poles. I have therefore tried to obtain this 
globular electricity with a single pole, and I have 
, succeeded in doing so by a very simple process. 
A rod, about half a centimetre in diameter, termi- 
nated by a needle of which the point is placed on 
a plate covered with gelatino-bromide of silver, is 
connected with the negative pole of a Wimshurst 
' machine, and the other pole is earthed. When 
the machine is in motion, one sees issue from the 
point of the needle one or several luminous globes 
which advance slowly and disappear abruptly after a 
few centimetres, leaving on the plate the trace of 
their trajectory. 

If, instead of employing a thick rod terminated by 
a needle, a thin rod were used, the formation of 
luminous spheres would not take place. The pheno- 

^ I.e, St. £lmo*s fire or corposants. — F. L. 


menon seems .to act — though probably it is produced 
quite otherwise — as if the electricity of the thick 
rod accumulated at the point of the needle after the 
fashion of a drop of liquid. ^ 

It is difficult to state precisely the part taken in 
these experiments by the gelatino-bromide of the 
photographic plate. Its presence facilitates the 
fesult, but is it indispensable ? Some authors 
claim to have obtained globular electricity with 
simple plates of glass or mica, but I have not 
succeeded in thus producing them. 

However that may be, the luminous spheres formed 
by one of the processes just indicated, possess very 
singular properties, notably a considerable stability. 
They can be touched and displaced with a strip of 
metal without being discharged.^ A magnetic field 
— ^t all events the one of rather weak intensity 
at my disposal — has no action on them. If these 
spheres only consist of agglomerated ions, these last 
must be in a very special state. Their stability can 
only proceed from extremely rapid whirling move- 
ments, similar to those of the gyroscope, which, as 
is well known, simply owes its equilibrium to the 
rotary motion which animates it. 

In the preceding experiments we have realized, 

' In a case of globular lightning observed at Autun, and quoted in 
the Comptes Rendus de I* Academic des Sciences, 29th August 1904, 
M. Roche reports that the globe of fire after travelling 500 metres, 
in which it carried away doors, and swept off three large chimney- 
stacks, created a great perturbation at the Sous- Prefecture, which was 
provided with a lightning-rod. The author draws this conclusion: 
** It would therefore seem that a lightning-rod has no action on globular 
lightning." This last fact can be connected with the impossibility 
noticed in my experiments of discharging an electric globule by 
touching it with a metallic body. 



with particles of dissociated matter, geometrical 
figures of a momentary stability which hardly 
survive the causes producing them. But it is 
possible to maintain for a fairly long time and on 
one surface certain forms of the electric fluid and 
to cause it to take the form of geometric plane 
figures with concise outlines. 

In speaking of the properties of ionized gases, I 
have called by the name of ionic fluid, that fluid 
which the ionized particles make up by their 
aggregation. Thanks to its inertia, it is easy, by 
following the method pointed out 
by Professor de Heen, to trans- 
form this into regular geometric 
figures possessing a certain per- 
manence. The experiment is 
very simple. Take a targe 
square plate of resin from 30 
to 40 centimetres in diameter, 
and electrify it by passing its 
surface over one of the poles of 
an electrical machine in motion. 
Then expose for several seconds 
the electrified face of this plate 
to two sources of ionization — 
for instance, two Bunsen burners 
at a distance of 5 to 6 centi- 
metres from each other. The 
ions starting from these sources 
come into contact with the plate, 
repel the electricity, and then, 
when face to face with each 
other, they halt and form a 
straight line (Fig. 16). This 

Flgs. 16 TO 19.— Ph 
giaphs of geonieti 
figures oblained liy i 
lining the ionic fluii 
pklm of rain. 


invisible line is rendered visible by dusting powdered 
sulphur on the plate by means of a sieve. After 
slightly shaking the plate, there will only remain on 
its surface the straight line traced by the ionic fluid. 

If, instead of two Bunsen burners, a certain 
number are placed so as to form the outlines of 
geometrical figures, you obtain on the plate varied 
images: triangles, hexagons, etc., as regularly as if 
they had been traced with a ruler (Figs. 17 to 19). 
It is evident that with an ordinary gas, you could 
produce nothing like this, since it would escape from 
the plate by diffusing through the atmosphere. 

In the different experiments above mentioned, we 
have materialized, crystallized as it were, for an 
instant the fluid, so immaterial in appearance, 
composed of the union of the elements proceeding 
from the dissociation of matter. We now begin 
to see how, with more complicated equilibria and 
above all with the colossal forces she has at com- 
mand. Nature has been able to create those stable 
elements which constitute material atoms. While 
in evolution towards the state of matter, the ether 
must, no doubt, have passed through intermediate 
phases of equilibrium similar to those indicated in 
this chapter, and also through various forms the 
history of which is unknown to us. 




§ I. Causes capable of Modifying Molecular and 

Atomic Structures. 

The first objection which occurs to the mind of 
the chemist to whom one sets forth the theory of 
the dissociation of matter, is the following: — How 
can bodies so stable as atoms— which appear to 
withstand the most violent reactions, since their 
weight is always recognized as invariable — dis- 
sociate either spontaneously or under such slight 
causes as rays of light hardly capable of influencing 
a thermometer ? 

To say, as I maintain, that mattet is a large 
reservoir of forces, simply means that there is no 
need to look outside it for the origin of the energy 
expended during dissociation, but this in no way 
explains how intra-atomic energy condensed under 
an evidently very stable form can free itself from 
the bonds which hold it. The doctrine of intra- 
atomic energy therefore supplies no solution to the 
question just put. It is unable to say why the 
atom, which is to all appearance the most stable 
of all things in the universe, can, under certain 
conditions, lose its stability to the extent of easily 




If we wish to discover the solution of this 
problem, it will first be, necessary to show, by 
various examples, that in order ,to produce in 
matter very great changes of equilibrium, it is 
not always the magnitude of the effort which 
counts, but rather the quality of that effort. Every 
equilibrium in Nature is only sensitive to the 
appropriate excitant, and it is this excitant which 
must be discovered in brder to obtain the effect 
sought. Once discovered, it can be seen that very 
slight causes can easily modify the equilibrium of 
atoms and bring about, like a spark in a mass of 
gunpowder, effects whose intensity greatly exceeds 
that of the exciting cause. 

A well-known acoustic analogy allows this differ^' 
ence between the intensity and the quality of the 
effort to be clearly shown from the point of view of 
the effects produced. The most violent thunder- 
clap or the most deafening explosion may be 
powerless to cause the vibration of a tuning-fork, 
while a sound, very slight but of suitable period, 
will suffice to set it in motion. When a tuning- 
fork starts vibrating by reason of the production near 
it of a sound identical with its own, it is said to 
vibrate by resonance. The part played by resonance 
in acoustics as well as in optics is now well known; 
it gives the best explanation of the phenomena 
of opacity and transparency. It can help to ex- 
plain, with all the facts I am about to state, that 
insignificant causes can produce great transforma- 
tions in matter. 

Although our means of observing the internal 
variations of bodies are very insufficient, facts, 
already numerous, prove that it is easy to profoundly 


change molecular and atomic equilibria, when they 
are acted upon by the proper agents. I shall confine 
myself to recalling a few of them. 

A simple ray of light, though its energy is very 
slight, by falling on the surface of substances, such as 
selenium, sulphide of silver, oxide of copper, platinum 
black, etc., modifies their electric resistance to a con- 
siderable extent. So, too, several dielectrics become 
birefringent when electrified. Boracite, again, which 
is birefringent at ordinary temperatures, becomes 
unirefringent when heated. Certain alloys of iron 
and nickel also become instantaneously magnetic by 
heat and lose their magnetism on cooling. Finally, 
if a transparent body placed in a magnetic field has 
a luminous ray passed through it, the rotation of 
the plane of polarization can be observed. 

All these changes in physical properties neces- 
sarily imply changes of molecular equilibria. Slight 
causes suffice to bring about these changes because 
the molecular equilibria are sensitive to these 
causes. Forces far greater, but not appropriate, 
would, on the contrary, have no effect. Take any 
salt — chloride of potassium, for instance. It can be 
ground, pulverized by the most powerful machinery 
without it ever being possible to separate the 
molecules of which it is composed. And yet, to 
dissociate these molecules, to separate what are 
called ions — that is to say, chlorine and potassium-^ 
it suffices, according to modern theories on elec- 
trolysis, to dissolve the substance in a liquid so that 
the solution is sufficiently diluted. 

Many similar examples can be given. To force 
apart the molecules of a steel bar it would have to 
be submitted to enormous mechanical strains ; yet it 


suffices to heat it slightly, if only by placing the 
hand upon it, for it to elongate. This elongation of 
a bar by the contact of the hand can even be made 
visible, as Tyndall showed, to a whole audience by 
* pieans of a lever and a mirror suitably arranged. A 
similar phenomenon is observed in water. It is 
almost incompressible under the very strongest 
pressure, and yet its temperature has only to be 
slightly lowered for it to contract. 

We can produce in a metal far more thorough 
molecular displacements than those effected by heat, 
for there are some which imply a complete change in 
the direction of the molecules. No mechanical force 
could cause such transformations; yet they are 
instantaneously effected by bringing a bar of iron 
near a magnet, when all its molecules instantly 
change their direction. 

The recent employment of high temperatures, 
formerly impossible of attainment, as well as the 
introduction of the high electrical potentials which 
have permitted new chemical combinations to be 
produced, naturally leads us to think that it would 
be especially by means of these enormous forces that 
certain transformations will be possible. No doubt, 
by these new means, it has been possible to 
create certain chemical equilibria hitherto un- 
known, but to modify instable matter there is 
no need of these gigantic efforts. This is proved 
when we see certain luminous rays of a fixed 
wave-length producing instantaneously in various 
substances the chemical reactions which generate 
phosphorescence, and radiations of shorter wave- 
length giving birth to converse reactions which no 
less instantaneously destroy this phosphorescence. 


A further proof is afforded when we note that the 
Hertzian waves produced by electric sparks trans- 
form, at a distance of 500 kilometres, the molecular 
structure of metal filings;^ or, again, when we 
observe that the neighbourhood of a simple magnet 
immediately changes, in spite of all intervening 
obstacles, the direction of the molecules of an iron 

In the dissociation of matter similar facts are 
observed. Metals, highly radio-active under the 
influence, of luminous radiations of a certain w-ave- 
length, are hardly so at all under the influence of 
radiations of one but slightly different. The same 
thing seems to occur here as in the phenomenon of 
resonance. It is possible, as I remarked above, to 
cause a tuning-fork or even a heavy bell to vibrate 
by producing close to them a note of a certain 
vibratory period, when the most violent noises may 
leave them insensitive. When we become better 
acquainted with the causes capable of slightly 
dissociating the aggregate of energy condensed in 
the atom, we shall certainly arrive at a more com- 
plete dissociation and be able to utilize it for 
industrial purposes. 

The whole of the preceding facts justifies my 
assertion that, in order to obtain important trans- 
formations of molecular equilibrium, it is not a 
question of the intensity but of the quality of the 
effort. These considerations enable it to be under- 

^ Is this the effect of the Hertzian waves? The different theories as 
to the manner in which the coherer operates are set out by M. Turpain 
{Les Ofuies EleciriqueSt pp. 237 et seq, Paris, 1902) with the remark 
that none are entirely satisfactory. Cf. the researches of M. A. Blanc 
on "Coheration," I^ev^te Scieniifique^ 30th June 1906.— F. L. 


Stood how structures so stable as atoms can be 
dissociated under the influence of such slight causes 
as a ray of light. If invisible ultra-violet radiations 
can dissociate the atoms of a steel block on which all 
the forces of mechanics would have no effect, it 
is because they form a stimulant to which matter is 
sensitive. The component parts of the retina are not 
sensitive to this stimulant, and this is why the ultra- 
violet light, capable of dissociating steel, has no 
action on the eye, which does not even perceive its 

Matter, insensitive to actions of importance, can 
therefore be, I repeat, sensitive to very minute ones. 
Under appropriate influences, a very stable body 
may become unstable. We shall see soon that 
sometimes imponderable traces of substances may 
at times powerfully modify the equilibria of other 
bodies and act in consequence as those excitants, 
light but appropriate, which matter obeys. 

§ 2. Mechanism of the Dissociation of Matter. 

According to the ideas now current on the con- 
stitution of atoms, every atom may be considered 
as a small solar system comprising a central part 
round which turn with immense speed at least a 
thousand particles, and sometimes many more. 
These particles therefore possess a great kinetic 
energy. Let some appropriate cause come to 
disturb their trajectory or let their speed of rotation 
become sufficient for the centrifugal force which 
results from it to exceed the force of attraction 
which keeps them in their orbits, and the particles 
of the periphery will escape into space by following 




the tangent of the curve they formerly trod. By 
this emission they will give birth to the phenomena 
of radio-activity. Such, in any case, is one of 
the hypotheses which may be provisionally for- 

When it was recognized that radio-activity was an 
exceptional property appertaining to only a very few 
bodies, such as uranium and radium, it was thought — 
and many physicists still think — that the instability of 
these bodies was a consequence of the magnitude of 
their atomic weight. This explanation vanishes before 
the fact shown by my researches that it is just those 
metals whose atomic weight is feeblest, such as 
magnesium and aluminium, which become most 
easily radio-active under the influence of light; 
while, on the contrary, it is bodies possessing a high 
atomic weight, like gold, platinum, and lead, which 
have the weakest radio-activity. Radio-activity is 
therefore independent of atomic weight, and probably 
very often due, as I shall explain later on, to certain 
chemical reactions of an unknown nature. Two 
bodies not radio-active sometimes become so when 
combined. Mercury and tin may be placed among 
bodies of which the dissociation, under the action 
of light, is the weakest: I have shown, however, 
that mercury became extraordinarily radio-active 
Under this same influence, so soon as traces of tin 
are added to it. 

All the interpretations which precede contain 
assuredly only the outlines of an explanation. The 
mechanism of the dissociation of matter is unknown 
to us. But what physical phenomenon is there 
whose ultimate causes are not equally hidden from 
our view ? 


§ 3. Causes capable of Producing the Dissociation of very 

Radio-active Substances. 

We have seen that various causes may produce 
the dissociation of ordinary matter. But in the 
dissociation of substances spontaneously very radio- 
active — radium and thorium, for instance — no ex- 
ternal cause seems to bring about the phenomenon. 
How, then, can it be explained ? 

Contrary to the opinions expressed at the commence- 
ment of researches into radio-activity, I have always 
maintained that the phenomena observed in radium 
arose from certain special chemical reactions, similar 
to those produced in the case of phosphorescence. 
These reactions take place between substances of 
which one is in infinitesimal proportion to the 
other. I only published these considerations after 
I had discovered bodies becoming radio-active in 
such conditions. Salts of quinine, for instance, 
are not radio-active. By letting them be slightly 
hydrated after desiccation, they become so, and 
remain phosphorescent while hydration lasts. Mer- 
cury and tin show no perceptible signs of radio- 
activity under the influence of light; but add 
to the former a trace of the latter, and its radio- 
activity at once becomes intense. These experi- 
ments even led me thereafter to modify en- 
tirely the properties of certain simple bodies 
by the addition of- minute quantities of foreign 

The disintegration of matter necessarily implies 
a change of equilibrium in the disposition of the 
elements which compose the atom. It is only by 
passing into other forms of equilibrium that it can 

^ I 


lose part of its energy, and, in consequence, can 
radiate anything. 

The changes of which it is then the seat differ 
from those known to chemistry in this fundamental 
point, that they are intra-atomic, while the usual 
reactions affecting merely the structure of the 
groupings of atoms are extra-atomic. Ordinary 
chemistry can only vary the disposition of the 
stones destined to the building of an edifice. In 
the dissociation of atoms, the very materials 
with which the edifice is constructed are trans- 

The mechanism of this atomic disaggregation is 
unknown, but it is quite evident that it allows of 
conditions of a peculiar order, very different from 
those hitherto studied by chemistry. The quantities 
of matter put in play are infinitely small and the 
energies liberated extraordinarily large, which is 
the opposite of that which we get in our ordinary 

Another characteristic of the intra-atomic reac- 
tions which produce radio-activity is that they seem 
to occur, as I said before, between bodies of which 
one is extremely small in quantity with regard to the 
other. These particular reactions, to which we will 
revert in another chapter, are mainly observed during 
phosphorescence. Pure bodies such as sulphide of 
calcium, sulphide of strontium, etc., are never phos- 
phorescent. They only become so on being mixed 
with very small quantities of other bodies; and they 
then form mobile combinations, capable of being 
destroyed and regenerated with the greatest ease, 
which are accompanied by phosphorescence or the 
disappearance of phosphorescence. Other clearly 


defined reactions, such as a slight hydration, can 
likewise produce at the same time both phosphor- 
escence and radio-activity. 

This conception that radio-activity had its origin 
in a special chemical process, has at last secured the 
favour of several physicists. It has, notably, been 
adopted and defended by Rutherford and Soddy. 

" Radio-activity," say these, " is accompanied by a succession 
of chemical changes in which new types of radio-active matter 
are being continuously produced. It is a process of equilibrium 
where the amount of new radio-activity is balanced by the loss 
of the radio-activity already produced. Radio-activity is main- 
tained by the continual production of new quantities of matter 
possessing temporary radio-activity."^ 

A radio-active body is, in fact, a body in course of 
transformation. Radio-activity is the expression of 
its never-ceasing leakage. Its change is necessarily 
an atomic disaggregation. Atoms which have lost 
anything are, from that very fact, new atoms. 

One might consider as singular — at all events, as 
little in accord with the observations in our labora- 
tories — the existence of chemical reactions continuing 
almost indefinitely. But we also find in phosphor- 
escence reactions capable of taking effect with 
extreme slowness. I have shown by my experi- 
ments on invisible luminescence that phosphorescent 
bodies are capable of retaining in the dark, and 
for two years after exposure to sunlight, the property 
of radiating, in a continuous manner, an invisible 
light capable of impressing photographic plates. 
Since chemical reactions can destroy phosphor- 
escence, and continue to act for two years, it will 
be understood that other reactions, such as those 

1 Philosophical Magazine ^ September 1902. 


capable of producing radio-activity, might last for 
very much longer. 

Though the amount of energy radiated by atoms 
during their disaggregation is very large, the loss 
of material substance which occurs is extremely 
slight, by reason of the enormous condensation of 
energy contained in the atom. M. Becquerel 
estimates the duration of one gramme of radium 
at a thousand million years. M. Curie contents 
himself with a million years. More modest still, 
Mr. Rutherford speaks only of a thousand years, 
and Sir William Crookes of a hundred years, for the 
dissociation of a gramme of radium. These figures, 
of which the first are quite fantastic, become more 
and more reduced as the experiments become more 
exact. Dr. Heydweiler,^ after direct weighings, 
estimates the loss in five grammes of radium at .02 
milligrammes in 24 hours. If the loss continued at 
the same rate, then five grammes of radium would 
lose one gramme of their weight in 137 years. We 
are already astonishingly far from the thousand 
million years imagined by M. Becquerel. Even 
Heydweiler's figures, from certain of my experi- 
ments, are still too high. He has put in a tube 
the body experimented on in bulk, while I have 
noted that the radio-activity of a same body in- 
creases considerably if the substance is spread 
over a large surface, which can be obtained by 
leaving to dry the paper used to filter a solu- 
tion of it. We thus reach the conclusion that 
five grammes of radium lose probably the fifth 
of their weight in twenty years and conse- 
quently that a gramme would last one hundred 

* Physikaiische Zeitschrift, 15th October 1903. 


years, which are exactly the figures given by 
Sir WiiHam Crookes. In reality it is only re- 
peated experiments which will finally settle this 

But even if we accepted the figures of a thousand 
years given by Mr. Rutherford for the duration of 
the existence of one gramme of radium, it would be 
sufficient to prove that if spontaneously radio-active 
bodies, such as radium, existed in the geological 
epochs, they would have vanished long since, and 
would consequently no longer exist. And this again 
goes to support my theory, according to which rapid 
and spontaneous radio-activity only made its appear- 
ance since the bodies in question have been engaged 
in certain peculiar chemical combinations capable 
of affecting the stability of their atoms, which 
combinations we may perhaps some day succeed 
in reproducing. 

§ 4. Can the Existence of Radium be Affirmed with 

Certainty ? 

If radio-activity be the consequence of certain 
chemical reactions, it would appear that an absolutely 
pure body cannot be radio-active. It w^s on this 
reasoning, supported by various experiments, that 
I based my assertion a few years ago that the 
existence of the metal radium was very problema- 
tical. In fact, although the operation of separating 
a metal from its combinations is very easy, it has 
never been possible to separate radium. 

What one obtains at the present day under the 
name of radium is in nowise a metal, but a bromide or 
a chloride of this supposed metal. I consider it very 


probable that if radium exists and it is ever success- 
fully isolated, it will have lost all the properties 
which render its combinations so interesting. But 
for a long time^ and for divers reasons I have 
predicted that radium will never be isolated, and, 
as the supposed process of isolation would be too 
simple not to have been tried by the possessors of 
sufficiently large quantities of radium, the complete 
silence observed upon these attempts is a strong 
presumption in favour of my hypothesis. The 
separation of barium from its salts is so easy 
that this was one of the first metals isolated by 

The preparation of the salts of radium enables us 
to guess the manner in which were possibly formed 
the unknown combinations which have given birth to 
radio-activity. One knows how salts of radium were 
discovered. M. Curie having noticed that certain 
uranium ores acted on the electroscope with more 
force than uranium itself, was naturally induced to 
endeavour to isolate the substance to which this 
special activity was due. The property registered by 
the electroscope of rendering air more or less a 
conductor of electricity being the only available 
means of investigation, it was the action on the 
electroscope which alone served as guide in these 
researches. It was through it alone, in fact, that 
one could ascertain in which part of the precipitates 
the most active substances were to be found. After 
dissolving th^ ore in various solvents and precipi- 
tating the products contained in these solvents by 
fitting reagents, the most active parts were, by 
means of the electroscope, set aside, re-dissolved and 

^ Cf. Revue Scieniifique, 5lh May 19CO. 


separated anew by precipitation, and th6se manipu- 
lations were repeated a great number of times. 
The operation terminated with fractional crystal- 
lization, and finally a small quantity of a very active 
salt was obtained. It is to the metal, not isolated 
yet, of the salt thus obtained that the name of radium' 
was given. 

The chemical properties of salts of radium are 
identical with those of the combinations of barium. 
Radio-activity apart, they only differ by certain rays 
in their spectra. The supposed atomic weight of 
radium, calculated from a very small quantity of 
salts of radium, varies so much with the different 
observers that nothing can be deduced from it as to 
the existence of this metal. 

Without being able to pronounce positively, I 
repeat that I believe the existence of radium to be very 
disputable. It is, at any rate, certain that it has 
not been possible to isolate it. I should much more 
willingly admit the existence of an unknown com- 
pound of barium capable of giving this metal radio- 
active properties. Radio-active chloride of radium 
seems to bear the same relation to inactive chloride 
of barium that sulphide of barium, impure but phos- 
phorescent, bears to sulphide of barium pure, and for 
that reason, non-phosphorescent. It suffices, as I 
have noted above, for traces of foreign bodies to be 
added to certain sulphides — those of calcium, barium, 
strontium, etc. — for them to acquire the marvellous 
property of becoming phosphorescent under the 
action of light. This phosphorescence, which may 
be produced by radiation acting for no more than 
one-tenth of a second and destroyed, as I have 
shown, by other radiations of equally short period. 


proves the existence of chemical combinations of 
extreme mobility. Phosphorescence is a phenomenon 
which hardly astonishes us because it has so long 
been known; but on reflection, it must be acknow- 
ledged that it is quite as singular as radio-activity 
and still less explicable. 

I will add that by operating with salts of radium 
but slightly active — that is to say, still mingled with 
foreign bodies — the r61e of the chemical reactions 
is very clearly apparent. Thus, for instance, the 
phosphorescence of these salts is lost by the action 
of heat and only reappears after the lapse of a few 
days. Humidity destroys it altogether. 

Whether, then, we take ordinary phosphorescence 
or radio-active properties, they both seem to be 
produced by chemical reactions the nature of which 
is totally unknown to us, but in which it seems one 
of the combining bodies is always in very small 
quantity compared to the other. 

Doubtless, the law of definite proportions tells us 
that substances can only combine in certain relative 
quantities. This merely proves that bodies only 
form stable equilibria — which are the only ones 
accessible to chemistry — when combined in certain 
proportions. The number of combinations that two 
or more bodies can form is perhaps infinite, but as 
they are not stable, we can only suspect their exist- 
ence when they are unaccompanied by marked 
physical phenomena. The combinations accom- 
panied by radio-activity or phosphorescence are 
most probably instable combinations of this nature. 

However this may be, the above theory greatly 
assisted me in my researches. It is owing to this 
theory that I was led to discover the radio-activity 


which accompanies certain chemical reactions, and 
to find combinations capable of enormously increas- 
ing the dissociation of a body under the influence 
of light, and, finally, to fundamentally modify the 
properties of certain simple substances. 





All the substances we have studied in the shape 
of products of the dissociation of matter, have 
presented characteristics visibly intermediate be- 
tween those of matter and those of the ether. 
Sometimes they possess material qualities, as the 
emanations from thorium and radium, which can 
be condensed like a gas and enclosed in a tube. 
They equally present certain of the qualities of 
immaterial things, like the last-named emanation 
which, in certain phases of its evolution, vanishes by 
transforming itself into electric particles. Here, then, 
is a complete transformation of a material body into 
an immaterial substance. But it is possible to go 

What are the characteristics which allow us to 
assert that a substance is no longer altogether 
matter without yet being ether, and that it con- 
stitutes something intermediate between these two 
substances ? 

It is only if we see matter lose one of its irre- 



ducible characteristics — that is to say, one of those 
of which it cannot be deprived by any other means 
whatever — that we are authorized to say that it has 
lost its quality of matter. 

We have already seen that these irreducible 
characteristics are not numerous, since up to the 
present only one has been discovered. All the 
usual properties of matter — solidity, form, colour, 
etc. — are destructible. A mass of rock can, by heat, 
be transformed into vapour. One property alone, 
the mass measured by the weight, remains invari- 
able through all the transformations of bodies and 
allows them to be followed and re-discovered, not- 
withstanding the frequency of their changes. It is 
on this invariability of the mass that the sciences of 
chemistry and mechanics have been built. 

Mass, as is well known, is simply the measure 
of inertia — that is to say, of that property of 
unknown essence which enables matter to resist 
motion or the changes of motion. Its magnitude, 
which can be represented by a weight, is an 
absolutely invariable quantity for any given body, 
whatever be the conditions in which it can be 
placed. We are therefore led to consider a substance 
of which the inertia, and consequently the mass, can 
by any means be rendered variable as something 
very different from matter. 

Now, it is just this variability of the mass — that 
is to say, of the inertia — which is noted in the 
electric particles emitted by radio-active bodies 
during their disaggregation. The variability of this 
fundamental property will allow us to state that 
the elements resulting from the dissociation of bodies, 
elements which besides differ so by their general 


properties from material substances, form a substance 
intermediate between matter and the ether. 

Long before the current theories as to the 
structure of the electric fluid, now supposed to be 
formed by the conjunction of particular atoms, it was 
noticed that it possessed inertia — that is to say, re- 
sistance to motion or to change of motion, but only 
quite lately has the measurement of this inertia been 
arrived at. The oscillating discharge of a Leyden jar 
was one of the first phenomena which revealed the 
inertia of the electric fluid. This oscillating dis- 
charge can be compared to the movements, .similarly 
due to its inertia, wlych a liquid poured into a U tube 
makes before reaching its position of equilibrium. 
It is likewise through inertia that the phenomena of 
self-induction are produced. 

So long as the inertia of electric particles could 
not be measured, it was allowable to suppose it to be 
identical with that of matter; as soon as it was 
possible to calculate their velocity from the in- 
tensity of the magnetic force necessary to deviate 
them from their trajectory, it became possible to 
measure their mass. It was then seen to vary with 
their speed. 

The first experiments on this point are due to 
Kaufmann and Abraham. By observing on a photo- 
graphic plate the deviation under the influence of 
two superposed magnetic and electric fields, they noted 
that the relation of the electric charge c^ carried by a 
radio-active particle, to the mass in of this particle, 
varied with its velocity. As it cannot be supposed 
that in this relation the charge changes, it is evident 
that it is the mass which varies. 

The variation of the mass of the particles with 


their speed is besides in agreement with the electro- 
magnetic theorj' of Hght, and had already been 
pointed out by various authors, Larmor amongst them. 
This variation of the mass would suffice to prove 
that substances which exhibit such a property are 
no longer matter. It is thus that Kaufmann deduces 

Fig. 20. — Cume ihnwhis "'« 1/ the futtdammtal piopertiit ef the 
substance iitiermtdicUe bilvieiH pctiilerable matiir aiid Iht impoiidet- 
al'le ether. — The mass, instead of being constani in mognitude, 
like that of matter, vaties with the s|>ce(I. 

from his observations that the electron, of which 
certain radio-active emissions are composed, " is 
nothing but an electric charge distributed over a 
volume or a surface of very small dimensions." 

By putting Abraham's equation into the form of a 
curve, it is easy to see the manner in which the 
mass of the elements of dissociated matter vary with 


their speed. Constant at first even for very great 
velocities, it increases abruptly and quickly tends 
to become infinite as it approaches the velocity of 

So long as the mass has not attained a speed 
equal to 20 per cent, of that of light — that is to 
say, not exceeding 60,000 kilometres per second, its 
magnitude, represented by i at the beginning, remains 
about the same (1.012). When the speed reaches 
half that of light — that is, 150,000 kilometres per 

^ To express these variations Max Abraham has given the following 

equation: — 


in which /.Iq represents the value of the electric mass for slight speeds, 
/3 = -, the ratio of the speed ^ of this mass to that c of light and 

In order to obtain a graphic representation of the variation of the 
mass acting as a function of its speed, I have set forth the above 

equation in a form in which the ratio ~ appears as an explicit 

function of the ratio /3 = — ; we take as abscissae the values of the 

ratio 3 s: X and as ordinates the values of the ratio — = v. 

The equation of the curve becomes then 

j,^ J-rL±£!iogii^-,1 

4X^\_ 2X l-X J 

The horizontal y ^ i corresponds to — = i and represents the 


constant magnitude of the mechanical mass. In order to detach the 
curve more quickly I have adopted a scale of ordinates equal to ten 
times that of the abscissae. The excessive reduction of the curve 
rendered necessary by the size of this volume has made the numbers 
hardly legible, t have calculated the figures which express the varia-> 
tions of the mass as a function of the speed to 8 places of decimals. 
The most interesting of these are given in the text. 


second — the mass has still only increased by one- 
tenth (1.119). When the speed equals three- 
fourths that of light, the increase of the mass is still 
very slight (1.369). When the speed equals nine- 
tenths that of light, the mass has not yet quite 
doubled (1.82); but as soon as the speed reaches 
.999 that of light, the mass increases sixfold (6.678). 

We are here very close to the speed of light, and 
the mass has as yet only increased sixfold; but it 
is now that the figures deduced from the equation 
begin to increase singularly. For the mass of the 
electric atom to become twenty times greater (20.49), 
its speed will only have to differ from that of light 
by the fraction of a millimetre. For its mass to 
become a hundred times greater, its velocity would 
have to differ from that of light by the fraction 
of a millimetre comprising fifty -eight figures. 
Finally, if the speed of the electric atom became 
exactly equal to that of light, its mass would be 
theoretically infinite. 

These last results cannot be verified by any experi- 
ment, and are evidently only an extrapolation.^ We 
must not, however, consider as a priori absurd the 
existence of a substance of which the mass would 
increase in immense proportions, while its already 
very great speed would only vary by the minute 
fraction of a millimetre. The considerable increase 
of an effect under the influence of a very small 
variation in the cause is observed in many physical 
laws which can be translated by asymptotic 
curves. The immense variations in size of the 
image of an object for a very slight displacement 

^ The word used by mathematicians for the process of finding new 
terms outside a series. — F. L. 



of that object when very close to the principal 
focus of a lens, furnish an example of this. Suppose 
an object placed at one-tenth of a millimetre from 
the focus of a lens with a focus of ten centimetres. 
The general equation of lenses shows that its image 
will be magnified a thousand times. If the object is 
brought nearer by one-hundredth of a millimetre, 
its image will, theoretically, be magnified a, hundred 
thousand times. If, lastly, the object is placed in 
the very focus itself, its image will, theoretically, be 
infinite. Every time a physical law can be trans- 
lated by curves similar to the above, the slightest 
variation in the variable produces extremely im- 
portant variations of the function in the neighbour- 
hood of the limit.^ 

Leaving these theoretical considerations and 
coming back to the results of experiments, we may 
say this: the particles produced during the dissocia- 
tion of matter possess a property resembling inertia, 
and in this they are akin to matter; but this inertia, 
instead of being constant in magnitude, varies with 
the speed, and on this point particles of dissociated 
matter are sharply differentiated from material atoms. 

The study of the properties of the inertia of these 
elements leads, as will be seen, to their being con- 
sidered something which, issuing from matter, 
possesses properties somewhat similar to, but yet 

* I must point out, by the w«iy — and this observation will explain 
many historical events— that it is not only physical, but many social 
phenomena which can l)e likewise defined by curves possessing the 
properties we have just stated, and in which, consequently, very small 
changes in a cause may produce very great effects. This is owing to 
the fact that when a cause acts fur a length of time in a same direction, 
its effects increase in geometrical progression, while the cause varies 
simply in arithmetical progression. Causes are the logarithms of effects. 


notably different from, those of material atoms. 
Representing one of the phases of the dematerializa- 
tion of matter, they are only able to retain a part of 
the properties of this last. We shall see in another 
chapter that the electric fluid likewise possesses 
properties intermediate between those of matter and 
those of ether. 

Some physicists have supposed — without, however, 
being able to furnish any proofs — that the inertia of 
matter is due to the electric particles of which it 
should be composed, and consequently that all the 
inertia of material substances is entirely of electro- 
magnetic origin.! There is nothing to indicate that 
material inertia can be identified, with that of the 
particles of dissociated matter. The mass of these 
last is only, in reality, an apparent mass resulting 
simply from its condition as an electrified body in 
motion. They appear, besides, to have a longi- 
tudinal mass (that which measures the opposition to 
acceleration in the direction of the motion), different 
from the transversal mass (that perpendicular to the 
direction of the motion). In every way it is evident 
that the properties of an element of dissociated 
matter differ considerably from those of a material 

* Cf, Professor J. J. Thomson in his Yale Lectures: — "The view I 
wish to put before you is that it is not merely a part of the mass of a 
lx>dy which arises in this way, but that the whole mass of any body is 
just the mass of ether surrounding the body which is carried along by 
the Faraday tubes associated with the atoms of the body. In fact, that 
all mass is mass of the ether, all momentum, momentum of the ether, 
and all kinetic energy, kinetic energy of the ether." {^Electricity and 
Matter^ pp. 50-51.)— F. L. 

^ The vicious circle of the argument attacked in this paragraph is 
th\is well set forth by Professor H. A. Wilson: — " It is now suggested 
that all matter is composed of electrons, so that all inertia is electro- 


Of what, then, are constituted these atoms which 
are supposed to be electric, and are emitted by all 
bodies during their dissociation ? The answer to 
this question supplies the link required between the 
ponderable and the imponderable. It is impossible, 
in the present state of science, to give a definition of 
a so-called electric particle, but we can at least say 
this: Substances neither solid, liquid, nor gaseous, 
which pass through obstacles, and have no property 
common to matter, except a certain inertia, and even 
then an inertia varying with their speed, are very 
clearly differentiated from matter. They are likewise 
differentiated from the ether, of which they do not 
possess the attributes. They therefore form a transi- 
tion between the two. 

Thus, then, the effluves emanating from spon- 
taneously radio-active bodies, or from bodies capable 
of becoming so under the influence of the numerous 
causes we have enumerated, form a link between 
matter and the ether. And, since we know that 
these effluves cannot be produced without the 

magnetic. Density, according to this view, is simply the number of 
electrons per unit volume. Electro-magnetic inertia — that is, all 
inertia— is due to the energy of the magnetic field produced by the 
moving charges of electricity. The energy of this magnetic field 
resides in the ether. According to Maxwell's dynamical theory, the 
electro-magnetic energy of the ether is due to motion of parts of the 
ether, these parts possessing motion. But the only kind of inertia which 
we really know is the inertia of matter, which is due to the electro- 
magnetic action of the electrons of which matter is made up. If 
inertia is due to electrons, then if we ascribe to parts of the ether the 
property of inertia, we ought to say that the ether contains so many 
electrons per unit volume. But the free ether is not supposed to con- 
tain any electrons; in fact, if we explain inertia by the energy of the 
magnetic fields produced by moving charges, then evidently to explain 
this energy by inertia in the ether is wn^rely to argue ia a circle.'* 
{Na/ure, 22nd June 1905.)— F.L. 


definitive loss of matter, we have a right to say 
that- the dissociation of matter realizes indisputably the 
transformation of the ponderable into the imponderable. 

This transformation, so contrary to all the ideas 
bequeathed to us by science, is yet one of the most 
frequent phenomena in nature. It is daily produced 
before our eyes; but as formerly there existed no 
reagent to show it, it was not seen. 



§ I. Radio-active and Electrical Phenomena. 

By pursuing our researches on the dissociation of 
matter, we have been progressively led, by the conca- 
tenation of experiments, to recognize that electricity, 
of which the origin is so entirely unknown, represents 
one of the most important products of the dissociation 
of matter, and in consequence can be considered as a 
manifestation of the intra-atomic energy liberated by 
the dissociation of atoms. 

We have seen in the last chapter that the particles 
issuing from the radio-active substances constitute a 
substance derived from matter and possessing pro- 
perties intermediate between matter and the ether. 
We shall now see that the products of the dissocia- 
tion of matter are identical with those disengaged 
by the electrical machines in our laboratories. 
This generalization duly established, electricity in 
its entirety, and not simply in some of its forms, 
will appear to us as the connecting link between the 
world of matter and that of the ether. 

We know that the products of the dissociation of 
all bodies are identical, and only differ by the extent 
of the power of penetration belonging to them and 



resulting from their difference of speed. We have 
established that they are composed — (ist) of positive 
ions of some volume at all pressures, and always com- 
prising in their structure some material parts; (2nd) 
of negative ions formed of electric atoms termed 
electrons, which can surround themselves in the 
atmosphere with material neutral particles; (3rd) of 
electrons disengaged from all material components, 
and able, when their speed is sufficient, to create by 
their impact X rays. 

These various elements are generated by all 
bodies which are dissociated, and especially by 
spontaneously radio-active substances. They are 
also found with identical properties in the products 
obtained from Crookes' tubes — that is to say, tubes 
through which, after exhaustion, electric discharges 
are sent. The only difference which exists betwfeen 
a Crookes' tube in action and a radio-active body in 
course of dissociation is, as we have already seen, 
that the second produces spontaneous!}^ — that is to 
say, under the influence of .actions ufiknown to us — 
that which the first produces o»Jy under the influence 
of electric discharges. 

ThiiSy then, electricity under various forms is 
always met with as the ultimate product of the 
dissociation of matter, whatever the process employed 
for its dissociation. It is this experimental fact 
which induced nfie to inquire if in a general way 
the electricity generated by any means — a static 
machine, for instance — might not be one of the forms 
of the dissociation of matter. 

But, if the analogy between a Crookes' tube and 
a radio-active body has at length become so evident 
that it is no longer disputed, it was less easy to 


establish an analogy between the phenomena taking 
place in that tube and electrical discharges in the air 
at ordinary pressure. Yet they are two identical 
things, though they differ in aspect. I will now 
demonstrate this. 

When two rods of metal connected with the poles 
of a generator of electricity are placed at a short 
distance from each other, the two electric fluids of 
contrary signs with which they are charged tend to 
recombine by virtue of their attractions. As soon 
as the electric tension becomes sufficiently strong to 
overcome the resistance of the air, they recombine 
violently, producing loud sparks. 

Air, by reason of its insulating qualities, offers 
great resistance to the passage of electricity ; but if 
we do away with this resistance by introducing the 
two electrodes in question into an exhausted receiver, 
the phenomena will be very different. Yet, in reality, 
nothing has been created in the tube. All that is 
found there, both ions and electrons, were already 
in the electricity which has been brought into it. At 
the most there could have been formed there new 
electrons arising from the impact of those derived 
from the source of electricity against the particles of 
rarefied gas still left in the tube. 

If the effects obtained by a discharge in a vacuum 
tube are greatly different from those produced by the 
same discharge in a tube filled with air, the reason is 
that in the vacuum the electric particles are not im- 
peded by molecules of air obstructing their course. 
In a vacuum alone can electrons obtain the speed 
necessary for the production of X rays when they 
strike against the walls of the tube. 

In no case, I repeat, are ions and electrons formed 


in the vacuum tube; they are brought there from 
outside. They are elements produced by the gene- 
rator of electricity. It is not in a Crookes' tube that 
matter is dissociated; it is taken there already dissociated. 

If this be actually so, we ought to be able to meet, 
in the electric discharges produced in the air by an 
electric machine, with the various elements — ions 
and electrons — of which we have noted the existence 
in the Crookes' tube, and which we know to be like- 
wise generated by radio-active bodies. 

Let us, then, examine the electricity furnished by 
the little static machines of our laboratories. We 
might take as a typical generator of electricity the 
most simple of all, a rod of glass or resin giving out 
electricity at a. tension of from two or three thousand 
volts, but its use would be inconvenient for many 
experiments. The majority of electrical machines 
for laboratory use, however, only differ from this 
elementary apparatus by the greater surface pre- 
sented by the body receiving friction, and because it 
is possible by the help of various artifices to collect 
separately the positive and negative electricity at two 
different extremities called poles. 

The electricity issuing from a static machine 
possesses, however, a considerable advantage from 
the point of view which interests us. Its output is 
very small, but the electricity issues from it at an 
extremely high tension, which may easily exceed 
50,000 volts. It is just this circumstance which will 
enable us to demonstrate in the electric particles shot 
forth by the insulated poles of a static machine a strict 
analogy with the particles emitted by radio-active 
bodies. The electricity of a battery is evidently 
identical with that of static machines, but as it is 


turned out at the tension of a few volts only, it can- 
not produce the same effects of projection. 

It is probable also that the friction on which the 
construction of the static machines is based con- 
stitutes one means of dissociation of the atom, and 
consequently brings intra-atomic energy into play. 
This, doubtless, does not act in the molecular dis- 
sociation of compound bodies on which the battery 
is based, and this is prob- 
ably why electricity is 
produced, in great quan- 
tity but at a very low 
tension, which in the best 
type of battery hardly 
exceeds two volts. If the 
output of a static machine 
could attain , that of a 
small ordinary battery, it 
would constitute an ex- 
FiG. 21. -Radiation cf ihe elec- ceedingly powerful^ agent 
Iric particles fioni a single pole, capable of producing an 
{/nsiaiitaiieoiis phoiosrafh.\ enoFmous amouut of in- 
dustrial work. Suppose an electric machine 
worked by hand and giving out electricity at a 
tension of 50,000 volts had an output of only two 
amperes— that is to say, the output of the very 
smallest battery — its yield would represent work to 
the extent of 100,000 watts, or 136 horse-power per 
second. Given that a considerable liberation of 
energy results from the dissociation of a very slight 
quantity of matter, the creation, in the future, of such 
a machine — that is to say, of an apparatus giving 
forth a power extremely superior to that expended in 
setting it in motion — can be considered possible. It 


is a problem of which the enunciation would have 

seemed altogether absurd some ten years ago. To 

solve it, it would be enough to find the means of 

placing matter in 

a state in which i 

it can be easily 

dissociated. Now, « 

we shall see that 2 

a simple ray of 

sunlight is a 

model agent of 

dissociation. It 

is probable that "* 

many others will 2 

be discovered. 

Let us now 

examine our or- 
dinary electric ^ 
machine at work " 
and inquire what ^ 
is disengaged by 

If the terminal 
rods forming the 
poles are very 
wide apart, there 
will be seen at 
their extremities 
sheaves of tiny 
sparks named 
Igrettes (Figs. 

Fig. 22. — Photc^aph of the aigreltes pro- 
duced by the particles emitted by one ol 
the poles of fl static machine, 

Flo. 23.— Positive and negative electric 
particles, which are formed at the two 
poles and attract each other. 

Fl<J. 24.— Concentration of the electric par- 
ticles into a few lines from which results 
a discharge in the shape aS sparks. 

itid 22), which are disengaged with 
t characteristic crackling noise. In the production 
of these elements dwells the fundamental pheno- 
menon. It is by examining their composition that 


one notes the analogies which exist between the 
products of radio-active bodies and Crookes' tubes, 
and those of an electrical machine. 

The eifects obtained with the elements which issue 
from the poles vary according to the disposition of 
these poles, and it is important to remember this first 
of all. 

If we connect the two poles by a wire of any 
length, in the circuit of which we intercalate a gal- 
vanometer, the deviation of its magnetic needle will 
reveal to us the silent and invisible production called 
an electric current. It is identical with that which 
traverses our telegraph lines, and is constituted of 
a fluid formed, according to current ideas, by the 
conjunction of electric particles called electrons, 
which the machine constantly generates. 

Instead of connecting the poles by a wire, let us 
bring them a little closer, keeping, however, a certain 
distance between them. The electric elements of 
contrary signs attracting one another, the aigrettes 
we have noticed elongate considerably, and with a 
fairly powerful machine they can be observed to 
form in the dark a cloud of luminous particles con- 
necting the two poles (Fig. 23). 

If we bring the poles still closer to one another, 
or if, without bringing them closer, we increase the 
tension of the electricity by means of a condenser, 
the attractions between the electric particles of 
contrary signs become much more energetic. These 
particles now condense over a smaller number of 
lines or over one line only, and the recombination of 
the two electric fluids takes place under the form of 
contracted, noisy, and luminous sparks (Fig. 24). 
But they are still constituted of the same elements 


as before, for the distance between the poles or the 
elevation of the tension are the only factors we have 
made to vary. 

The various effects we have just described are, 
naturally, very different from those we observe when 
the discharge occurs in a globe in which the air has 
been more or less rarefied. The absence of the air 
produces these differences, but this gas exercises 
no action on the electric elements disengaged by 
generators of electricity. Of what do these elements 
consist ? 

§ 2. Composition and properties of the elements emitted 
by the poles of an electric machine. Their analogy 
with the emissions of radio-active bodies. 

To analyse these elements, they must be studied 
before the recombination of the electric particles — 
that is to say, when the poles are far apart and dur- 
ing the production of the aigrettes mentioned above. 

We shall meet in them with the fundamental 
properties of the emissions of radio-active bodies, 
notably those of rendering air a conductor of 
electricity and of being themselves deviated by a 
magnetic field. From the positive pole of the 
machine start positive ions: from the magnetic 
pole start those atoms of pure electricity of defined 
magnitude termed electrons. But in opposition to 
what happens in a vacuum, these electrons im- 
mediately become the centre of attraction for 
gaseous particles and transform themselves into 
negative ions identical with those produced by the 
ionization of gases and in all forms of ionization. 

These emissions of ions are accompanied by 


secondary phenomena, heat, light, etc., which we 
will examine later on. They are also accompanied 
by a projection of metallic dust torn from the poles, 
the speed of which, according to J. J. Thomson, can 
attain 1800 metres per second — that is to say, about 
double the speed of a cannon ball. 

The speed of projection of the ions which together 
form the aigrettes of the poles of a static machine, 
depends, naturally, on the electric tension. By 
raising it to several hundred thousand volts with a 
high frequency resonator, I have succeeded in com- 
pelling the electric particles of the aigrettes to pass 
through, visibly (Figs. 25 and 26), and without 
deviation, plates of insulating bodies half a millimetre 
in thickness. This is an experiment made some 
time back with the collaboration of Dr. Oudin which 
I have already published with confirmatory photo- 
graphs. In the experimental part of this book will 
be found the technical directions necessary for 
repeating it. Notwithstanding its importance^ it 
made very little impression on physicists, though it 
was the first time that any one had succeeded in 
visibly transpiercing matter by electric atoms. By 
placing a glass plate becween the barely separated 
poles of an induction coil, it can, as has long been 
known, be easily pierced ; but this 4S a simple 
mechanical action. The aigrettes in our experiment 
go through bodies without in any way aifecting 
them, just as does light. The direction of the charge 
proves that they are composed of positive ions. 

^ So far as I know it has been noticed only by a distinguished 
English electrician,. Professor Fleming, who, in one of his lectures 
on Ebctric Oscillations {Cantor Lectures^ 1900)1 describes it as 


FlO. 25. — The visible passage through a malerial obstacle fanned ef a 
plati af glass or ebsnile. The effluves hive been outlined in dots 
as they appear to the eye. The next digram represents the 
pfaotogtaph of the phenomenon. The dots have disappeaied, 
through the enforced prolongation of the exposuie. 



The emission by the poles of an electric machine of 
electrons afterwards transformed into ions is accom- 
panied by various phenomena which are met with 
in radio-active bodies under hardly different forms. 
To study them it is preferable to have points at the 
end of the poles of the machine. It is then easily 
verified that what 
issues from an elec- 
trified point is iden- 
tical with that which 
issues from a radio- 
active body. 

The only actual 
difference is that the 
point does not at or- 
dinary pressure pro- 
duce X rays. When 
it is desired to ob- 
serve these latter, 
the point must be 
connected with a 
conductor allowing 
the discharge to 
take place in an 
exhausted globe. 
In this case, the 
production of X 
rays is abundant 
enough, even though only one pole be used, to render 
visible, on a screen of platino-cyanide of barium, 
the bones of the hand. 

The non -production of X rays is otherwise in 
accordance with the theory. The X rays are only 
generated by the impact of electrons having a great 

Fio. aG. — Photograph of the effiuves 
proceeding from the dsmalei 
of matter during their passnge through 
a milerial obstacle such as a jilale of 
glass or of ebonite. 



speed. Now, electrons formed in a gaseous medium 
at atmospheric pressure immediately change into 
ions by the addition of a retinue of neutral particles, 
and in consequence of this surcharge cannot keep 
up the speed necessary to generate X rays. 

Besides this property of generating X rays, which, 
moreover, is not common to all radio-active bodies, 
the particles which disengage themselves from an 
electrified point are, I repeat, in every way com- 
parable to those resulting from the dissociation of the 
atoms of all bodies. They render, in fact, air a con- 
ductor of electricity, as Branly showed long since, and 
are, as J. J. Thomson proved, deviated by a magnetic 

The projection of particles of dissociated matter — 
that is to say, of ions — against the air molecules 
produces what is called the electric wind, by which a 
lamp can be extinguished and a whirl made to re- 
volve, etc. It is in nowise due, as is constantly 
stated in all treatises on physics, to the electrification 
of the particles of the air, for a gas cannot be elec- 
trified by any process, save when it is decomposed. 
It is the kinetic energy of the ions transmitted to the 
molecules of the air which causes the displacement 
of these last. 

The ions emitted by the points with which we have 
equipped the poles of an electric machine can pro- 
duce fluorescent effects very similar to those observed 
with radium. They allow us to imitate the effects of 
the spinthariscope, which renders the dissociation of 
matter visible. One has only, according to M. Leduc, 
to bring within a few centimetres of a screen of 
platino-cyanide of barium in the dark a rod ter- 
minating in a very fine point connected with one of 


the poles — the positive one for choice— of a static 
machine, the other pole being earthed. If the screen 
be then examined with a magnify ing-giass, exactly 
the same shower of sparks as in the spinthariscope 
will be observed, and the cause is probably identical. 
The ions which issue from the poles of a static 
machine are not, as a rule, very penetrating — no more 
so, in fact, than the ions which form 99 per cent, of 

Fig. 27. — Impressions produced by ions issuing 
from an electiiliecl point through a sheel of 
blacl< paper. 

the emission of radium. However, I have been able 
to obtain very clear photographic impressions through 
a sheet of black paper by raising the electric tension 
sufficiently (Fig, 27). 

It is sufficient to place the object to be reproduced 
— a medal, for instance — over a photographic plate 
placed on a sheet of metal connected with one of the 
poles, while above the metal is fixed a rod com- 
municating with the other pole. A few small sparks 


suffice. The reproduction thus obtained cannot be 
attributed to the ultra-violet light produced by the 
discharge, seeing that the medal is separated from 
the plate by a sheet of black paper, and that under 
these conditions it is evident no light, visible or 
invisible, would succeed in producing an impression 
of the details of the medal. This phenomenon is, 
however, rather complex, and its thorough discussion 
would carry us too far. Hence I do not insist on 
the point. 

The ions emitted by electrified points are most 
often accompanied by the emission of light, a pheno- 
menon likewise observed in certain radio-active bodies. 
The spectrum of this light is singularly spread out. 
It varies, in fact, according to my researches, from 
Hertzian waves not more than two or three milli- 
metres long up to ultra-violet rays, of which the 
length is under A = .230/x. If a solar diffiraction 
spectrum be reckoned at one centimetre in length, 
the spectrum of the electrified points would be on 
the same scale about thirty metres long. The pro- 
duction of ultra-violet light in the spectrum of 
electric sparks has long been known and utilized, 
but it is, I think, M. Leduc who first pointed out its 
presence in the aigrettes from points. 

Yet there remained in my mind a doubt as to its 
existence. In the whole region round an electrified 
point there exists an intense electric field capable of 
illuminating at some distance a Geissler tube, and per- 
haps also capable of illuminating fluorescent bodies- 
It was therefore necessary to eliminate its action. 

To separate the action of the ultra-violet light from 
that which might be due to the electric field, I made 
use of the large ra-plate machine of Dr. Oudin, whose 


action is so powerful that the aigrettes produced will 
illuminate a screen of platino-cyanide of barium or 
a Geissler tube at a distance of several metres. 

The separation of the action of the electric field 
from that of the ultra-violet light has been realized 
in the most categorical manner by the following 
experiment effected with the co-operation of Dr. 
Oudin : — 

Within a wooden cage enveloped in metallic gauze 
connected with the earth — so as to obviate all electric 
action — are placed Geissler tubes and metal plates, 
on which are traced letters with powdered platino- 
cyanide of barium dissolved in gum arabic. It is 
then found that the Geissler tubes, which outside 
the cage shine brightly, entirely cease to be luminous 
as soon as they are placed within it; while, on the 
contrary, the letters traced with the platino-cyanide 
and enclosed in the metallic cage continue to shine. 
The illumination of these latter is therefore solely 
due to the ultra-violet light. 

It results, then, from what precedes that the forma- 
tion of electric aigrettes is accompanied by an 
enormous production of invisible light. With a 
high frequency resonator the quantity is so great 
that illumination of the platino-cyanide can be pro- 
duced up to a distance of more than five metres. 

-It is not for me to inquire here how ultra-violet 
light acts on fluorescent bodies. It is admitted, since 
the days of Stokes, that fluorescence comes from 
the transformation of invisible ultra-violet waves into 
larger and, for that reason, visible waves. But I must 
remark, by the way, that it would perhaps be simpler 
to suppose that fluorescence is due to the production — 
binder the influence of ultra-violet light, the energetic 


ionizing action of which is well known — of slight 
atomic electric discharges from bodies which their 
structure renders capable of fluorescence. 

In order to determine the limits of the ultra-violet 
produced in the foregoing experiments, I made use 
of various screens placed on the platino-cyanide 
screen, having first ascertained their transparency by 
means of the spectrograph used in former researches. 
The active part of the ultra-violet — that is to say, that 
which is capable of producing fluorescence — extends 
up to about A = .230/^. 

But an electrified point in discharge is not only a 
source of ultra-violet light; it also emits Hertzian 
waves, a fact totally unknown before my researches. 
I have indicated, in the experimental part of this 
work, the means employed to reveal them. By 
reason of their slight length, which, probably, does 
not exceed two millimetres, they hardly propel them- 
selves farther than forty to fifty centimetres.^ 

* The Hertzian wave which always accompanies electric sparks is 
no longer electricity but is a phenomenon of vibration of the ether, and 
only appears to differ from light in length of wave. Though it has 
gone forth from electricity, it is able to re-assume the ordinary 
electric form whenever it touches any substance. It then communi- 
cates to the latter a charge verifiable by the electroscope, and can 
produce sparks. 

Between the Hertzian wave and electricity there is a difference of 
the same order as that which exists between radiant heat and heat 
by conduction, which were formerly confounded. They are two very 
different phenomena, since one occurs with matter, the other in the 
ether. They can, however, transform themselves one into the 
other. A substance when heated emits waves in the ether analogous 
to those produced by a stone thrown into water. These waves on 
striking a material substance become absorbed by it and are transformed 
into heat. So soon as the material substance is heated it at once 
radiates calorific waves into the ether in the same way as the Hertzian 
wave electrifies a substance when it touches it and imparts to it the 
faculty of emitting in turn other Hertzian waves. 


This production of Hertzian waves, visible light 
and invisible ultra-violet light, the constant com- 
panions of all emissions of electric particles, must be 
borne in mind, for it will furnish us later on with the 
key to the final process of the transformation of 
matter into vibrations of the ether when we take up 
this question in another chapter. 

To sum up the foregoing, we may say that a body 
electrified by any means, notably friction, is simply 
a body whose atoms have undergone the commence- 
ment of dissociation. If the products of this dis- 
sociation be emitted in a vacuum, they are identical 
with those generated by the radio-active substances. 
If emitted in the air, they possess properties which 
only diifer from those of radio-active emissions, 
from their speed being less. 

Looked at from this point of view, electricity 
appears to us as one of the most important phases 
of the dematerialization of matter, and, consequently, 
as a particular form of intra-atomic energy. It con- 
stitutes, by reason of its properties, a semi-material 
substance intermediate between matter and the 




I HAVE shown that the electric particles and the 
fluid they form by their conjunction possess an inertia 
of a special nature differing from that of matter, 
which, joined to other properties, allows us to consider 
electricity in all its forms as composing an inter- 
mediate world between matter and the ether. 

We shall again meet with the properties of this 
intermediate world when we compare the laws of the 
flow of material fluids with those which regulate the 
distribution of the electric fluid. The differences 
between these different fluids are too visible for it 
to be necessary to indicate them at length. The 
electric fluid possesses a mobility which allows it 
to circulate in a metallic wire with the speed of 
light, which would be impossible for any material 
substance. It escapes the laws of gravitation while 
the equilibria of material fluids are governed by 
these laws alone, etc. 

The differences are therefore very great, but the 
analogies are so likewise. The most remarkable of 
them is formed by the identity of the laws governing 
the flow of the material fluids and of the electric 
fluid. When one knows the former one knows the 
latter. This identity, which has taken some long 
time to establish, has now become classic. The 



most elementary treatises lay stress at every page on 
the assimilation which can be established between 
the distribution of electricity and that of liquids. 
They are careful, nevertheless, to point out that this 
assimilation is symbolical, and does not apply in 
every case. On looking a little closer into the 
matter, it has to be acknowledged, however, that it 
is in nowise a question of a simple assimilation. In 
a recent work^ the learned mathematician Bjerkness 
has shown that we have only to employ a certain 
system of electrical units for "the electric and 
magnetic formulas to become identical with the 
hydro-dynamic formulas." 

A few examples will at once make evident the 
resemblance of these laws. To give them more 
authority I borrow them from a work of Cornu, pub- 
lished a few years ago.^ 

It must first be remarked that the fundamental 

law of electricity, that of Ohm M = -)> might have 

been deduced from that movement of liquids in con- 
duit pipes the properties of which have long been 
known to engineers. 

Here is, however, for the most important cases, 
the comparison of the laws governing these various 
phenomena. One of the two columns applies to 
material fluids, the other to the electric fluid. 

The outflow of a liquid per unit 
of time, through a communication 
tube, is proportional to the differ- 
ence of level and in inverse ratio 
to the resistance of the tube. 

The intensity of 'a current in a 
given wire is proportional to the 
difference of potential existing 
between the two extremities, and 
in inverse ratio to the resistance. 

^ Bjerkness, Les actions hydroiynamiques h distance, 
^ Cornu, Corritation des phinotnlnes d^etectriciti statique et dyni- 



In the fall of a liquid through 
a communication pipe from one 
given level to another likewise 
fixed, the work at^ our disposal is 
equal to the product of tha quan- 
tity of liquid by the difference in 
the levels. 

The height of the level in a 
vessel increases in proportion to 
the quantity of liquid poured into 
it, and in inverse ratio to the 
section of the vessel. 

Two vessels filled with liquid 
placed in suitable communication 
with each other are in a state of 
hydrostatic equilibrium when their 
levels are the same. 

The total quantity of liquid is 
then divided in proportion to the 
capacities of the vessels. 

In the passage of electricity 
through a wire from one given 
potential to another likewise fixed, 
the available work of the electric 
forces is equal to the product of 
the quantity of electricity by the 
difference of potential (fall) of 

The electric potential of a con- 
ductor increases in proportion to 
the quantity of electricity yielded 
(charge), and in inverse ratio to 
the capacity of the conductor. 

Two electrified conductors put 
in connection with each other are 
in a state of electrostatic equili- 
brium when their potentials are 
the same. 

The total electric charge is 
then divided in proportion to the 
capacities of the conductors. 

Cornu, who has carried these analogies much 
further than I have here done, is careful to remind 
us that these are assimilations of everyday use in 
practice, "an electric canalisation must be treated 
like a distribution of water: at every point on the 
system one must make certain of the pressure neces- 
sary for the output.'* 

All the foregoing phenomena observed with the 
electric fluid as with the material fluids are the 
result of the disturbances of equilibrium of a fluid 
which obeys certain laws in regaining its equilibrium. 
Disturbances of equilibrium producing electric 
phenomena manifest themselves whenever by any 
means — friction, for instance — a separation is made 
between the two elements positive and negative, of 


which the electric fluid is supposed to be formed. 
The re-estabhshment of the equilibrium is character- 
ized by the recombination of these two elements. 

It is only, as I have already said, the phenomena 
resulting from disturbances of equilibrium which are 
accessible to us. The neutral electric fluid — that is 
to say, the electric fluid which has not undergone 
any change of equilibrium — is a thing we may assume 
to exist, but no reagent reveals it. But it is natural 
to believe that it has an existence as real as that of 
water enclosed in different reservoirs, between which 
there is no alteration of level capable of producing a 
mechanical effect which would reveal the pressure of 
the liquid. What we call electricity proceeds solely 
from phenomena resulting from the displacement of 
the so-called electric fluid or of its elements. 

We have just shown that electricity in motion 
acts like a material fluid, but why should these two 
substances, evidently so different, obey the same 
laws? Can the analogy of effects indicate the 
analogy of causes ? 

We know that this can nowise be. Gravity has 
no appreciable action on electricity, while it is the 
sole reason of the laws governing the flow of 
liquids. If a liquid passes from a higher to a lower 
level, it is because it obeys gravitation, which is not 
at all the case with electricity. The potential of a 
fall of water — that is to say, the difference in height 
between its starting-point and its destination — is 
entirely due to gravity; and if water stored at a 
certain height represents energy, it .is because it 
is attracted towards the centre of the earth — an 
attraction which the walls that imprison it alone 
prevent its obeying. When, by tapping the reser- 


voir, the water is allowed to flow, its fall produces, 
by reason of the earth's attraction, a force corre- 
sponding to that used in raising it. Once on the 
level of the ground, it can no longer produce 

If the gravitation which governs the flow of liquids 
is totally foreign to the phenomena noted in the 
circulation of the electric fluid, what is the cause of 
this last ? We know that this cause acts exactly like 
gravitation, but that, perforce, it differs fronl it. 
Although its inmost nature is unknown to us, we 
can imagine it, for observation teaches us that the 
electric fluid, by virtue of the reciprocal repulsion 
of its molecules, presents a tendency to expansion 
which is termed tension. This tendency to ex- 
pansion is also observed in gases, but it there 
diffiers from that of the electric fluid. This last may, 
in fact, be retained on the surface of any insulated 
body, while gases diifuse immediately unless confined 
by the walls of a hermetically sealed vessel. All 
modes of energy, whether appearing in the form of 
quantity or of tension, obey the same general laws. 

Thus we see continually occurring analogies — 
sometimes close, sometimes distant — between ma- 
terial things and things no longer material. It is 
precisely to the nature of the analogies between the 
ether and matter that are due the differences and 
the resemblances we have noted. 



We have just shown the analogies of the electric 
and material fluids, and have noted that the laws of 
their distribution are identical. 

These analogies become very slight, and even 
finally disappear when, instead of examining elec- 
tricity in a fluid state, we study the properties of 
the elements which appear to form this fluid. We 
know that, according to current ideas, it is composed 
of particles called electrons. This conception of a 
discontinuous — that is to say, granular — structure of 
electricity, which goes back to Faraday and Helm- 
holtz, has been greatly strengthened by recent 
discoveries. Suitably interpreted, it will enable us 
to bring together in a bird's-eye view not only the 
phenomena called radio-active, but also those pre- 
viously known in electricity and optics, such as the 
voltaic current, magnetism, and light. The majority 
of these phenomena may be produced by simple 
changes of equilibrium and movement of electric 
particles — that is to say, by displacements of the 
same thing. This we shall now demonstrate. 

Instead of taking a hypothetical body such as an 
electric atom or an electron, we will take in its stead, 
in the majority of cases, a small electrified metal 
sphere. This simple substitution, which does not 



modify the theory, has the advantage of making 
experimental verifications possible. 

According to whether this sphere is at rest, or in- 
motion, or stopped when in motion, it will, as we 
shall see, produce the whole series of electrical and 
luminous phenomena. 

Let us take, then, a little metallic sphere, insu- 
late it by any of the ordinary means, and begin by 
electrifying it. Nothing can be more simple, since it 
has only to be placed in contact with a hetero- 
geneous substance. Two different metals separated 
after contact, remain, as is well known, charged with 
electricity. Electrification by friction, on which the 
old machines were based, only represents one par- 
ticular case of electrification by contact. Friction, 
in fact, only multiplies and renews the heterogeneous 
surfaces present. 

This settled, let us remove our sphere to a little 
distance from the body with which it has first been 
put in contact. We then discover, by various means, 
that it is bound to this last by lines called lines 
of force, to which J. J. Thomson attributes a 
fibrous structure. These lines tend to bring together 
the bodies between which they exist, and have the 
property of repelling each other.^ Faraday compared 
them to springs stretched between the bodies. It is 
the extremities of these springs which constitute 
electric charges. 

Let us now remove our sphere to a great distance 
from the substance which served to electrify it 
by its contact. The lines of force which con- 
nect the two bodies remain attached to each of 

^ See the photographs of these repulsions of lines of force, or, rather, 
of particles going in the direction of lines of force, Fig. 6, p. 164. 


them and radiate in straight lines into space.^ It is 
to them as a whole that the name of electric field 
is given. 

If our sphere thus electrified and surrounded by 
radiating lines of force be well insulated, it will 
preserve its electric charge and produce all the 
phenomena observed in static electricity: attraction 
of light bodies, production of sparks, etc. 

In this state of repose the electrified sphere 
possesses no magnetic action, as is proved by its 
absence of effect on a magnetized needle. It can 
only acquire this property after it has been set in 
motion. Let us, then, put it in motion and suppose 
its speed to be uniform. Our electrified sphere will 
acquire, from the mere fact of this motion, all the 
properties of an ordinary voltaic current — that is to 
say, the current which circulates along the telegraph 
wires. It is even supposed, by the present theory, 
that there can be no other current than that pro- 
duced by the movement of electrons. 

But since our electrified sphere in motion acts in 
the same manner as a voltaic current, it ought to 
possess all its properties, and consequently its 
magnetic action. As a fact, it is surrounded, by its 
very motion, by circular lines of force constituting 
a magnetic field. These lines envelop the trajectory 
of the electrified body, and are superposed on its 
electro-static field, composed, as we have said, of 
radiating straight lines. 

This magnetic field which surrounds an electrified 
body in motion is not at all a merely theoretical view, 
but an experimental fact revealed by the deviation 

* See p. 163, Fig. 4, for a photograph representing, fairly correctly, 
the lines of force of a body electrified in a state of repose. 


imparted to a magnetized needle placed near it.^ The 
existence of these circular lines of force surrounding 
a current can be easily shown by passing it through 
a straight rod of metal piercing, at right angles to its 
plane, a sheet of cardboard sprinkled with metal 
filings. These filings, attracted by the magnetic 
field of the current, arrange themselves in circles 
round the rod. So that by the mere fact of being 
set in motion an electrified body acquires the 
properties of an electric current and of a magnet. 
This is equivalent to saying that any variation of an 
electric field produces a magnetic field. 

But this is not all. We have supposed the speed 
of our electrified sphere in motion to be uniform. 
Let us now vary this motion, either by moderating it 
or by accelerating it, and new phenomena very 
different to the above will appear. 

The change of speed of the electrified body has 
for its consequence, by reason of the inertia of the 
electric particles, the production of the phenomena 
called phenomena of induction — that is to say, the 
birth of a new electric force which makes itself felt 

^ Rowland was the first to prove, by a memorable experiment (the 
origin of all the current theories), that an electrified body in motion 
possesses all the properties of an electric current which follows the 
direction of the movement, and is consequently surrounded by a magnetic 
field. An insulating disc covered with metallic sectors charged 
with electricity, when set in motion, will cause a magnetic needle 
placed immediately above it to deviate exactly in the same way as 
would an ordinary voltaic current. Some few years ago a student in 
M. Lippmann's laboratory thought he was able to dispute this funda- 
mental experiment, but a learned physicist, M. Pender, compelled 
him to acknowledge his error by pointing out that if he failed to obtain 
this deviation which proved the existence of a current, it was simply 
because he had had the unlucky idea of covering the metallic sectors 
with an insulating varnish which absorbed the electricity. 


in a direction perpendicular to that of the magnetic 
lines, and consequently in the direction of the current. 
The variation of a magnetic field, therefore, has the 
effect of producing an electric field. It is on this 
phenomenon that are based many machines for the 
commercial production of electricity. 

Another result of the superposition of this new 
force on the magnetic field of the electrified body 
whose movement has been modified, is the apparition 
in the ether of vibrations which propagate themselves 
therein with the speed of light. It is waves of this 
kind that are made use of in wireless telegraphy. In 
the electro-magnetic theory of light accepted by all 
modern physicists, it is even supposed that these 
vibrations are the sole cause of light as soon as they 
are rapid enough to be perceived by the retina. . 

All through the foregoing we have supposed that 
the electrified body in motion is displaced in the air 
or in a gas at ordinary pressure. If it be made to 
move in a very rarefied medium, still new pherior 
mena of a very different kind appear. These are the 
cathode rays, in which the electric atom seems to be 
entirely disengaged from all material support, and the 
X rays generated by the impact of these electric 
atoms against an obstacle. Here, evidently we can no 
longer have recourse to our picture of an electrified 
sphere of metal. We must consider the electric 
charge alone, freed from the material sphere which 
carried it. 

Thus, then, as we said at the first, it is sufficient to 
modify the movement and the equilibrium of certain 
particles to obtain all the phenomena of electricity 
and light. 

The above theory is verified, in most cases, by 


experiments. It is even, in reality, only a theoretical 
translation of experiment. So far as the phenomena 
of light are concerned, it had, however, prior to the 
researches of Zeeman, received no experimental con- 
firmation. It was only by hypothesis that it was sup- 
posed to be the atoms of electricity, and not matter, 
which entered into vibration in incandescent bodies. 
It was thought that a flame contained electrons in 
motion round a position of equilibrium at a speed 
sufficient to give birth to electro-magnetic waves 
capable of propagating themselves in the ether, 
and of producing when rapid enough the sensation 
of light on the eye. 

To justify this hypothesis it was necessary to 
be able to deviate the electrons of flames by a mag- 
netic field, since an electrified body in motion is 
deviable by a magnet. It is this deviation that 
Zeeman succeeded in producing by causing a 
powerful electro-magnet to act on a flame. He 
then noticed that, on examining this flame with 
the spectroscope, the rays of the spectrum were 
deviated and doubled. From the distance be- 
tween the spectrum lines thus separated, Zeeman 

was able to deduce the ratio — existing between the 


electric charge e of the electron in the flame and its 

mass m. This ratio was found to be exactly equal to 

that of the cathode particles in the Crookes tube* 

This measurement helps to prove the analogy of an 

ordinary flame with the cathode rays and radio-active 


One here sees the fundamental part played by 

electrons in current ideas. A great number of 

physicists consider that they form the sole element 



of the electric fluid. " A body positively electrified," 
says one of them, " is simply a body which has lost 
part of its electrons. The carrying of electricity from 
one point to another is realized by the transport of 
electrons from the place where there is an excess of 
positive electricity to the place where there is an 
excess of negative electricity." The aptness of 
elements to enter into chemical compounds should 
depend on the aptness of their atoms to acquire a 
charge of electrons. Their instability should result 
from the loss or excess of their electrons. 

The theory of electrons allows us to explain 
many phenomena in a very simple manner, but 
it leaves many uncertainties still existing. By 
what mechanism does the propagation of elec- 
trons take place so rapidly in conducting bodies — 
a telegraph wire, for instance ? How is it that 
electrons pass through metals while these last 
form an absolute obstacle to the most violent 
electric sparks ? Why is it that electrons which 
can pass through metals are unable to cross an 
interval of i millimetre of vacuum, as is proved by 
bringing together the two electrodes of an induction 
coil in a tube in which a complete vacuum has 
been made (Hittorf tube) ? Even with a coil 
giving a spark of 50 centimetres — that is to say, 
one able to pass through 50 centimetres of air, 
the electricity is powerless to overcome i millimetre 
of vacuum.-^ 

^ By substituting fine needles for the electrodes I have sometimes 
obtained the passage of the current, but I draw no conclusions from 
the experiment, not being positive as to whether the vacuum in the 
tube was complete. But Cooper Hewitt has shown that the electric 
particles can be compelled to traverse a complete vacuum by first pro* 
ducing between the electrodes a short circuit. 


The electron • has become at the present day a 
sort of fetish for many physicists, by means of which 
they think to explain all phenomena. There has 
been transferred to it the properties formerly attri- 
buted to the atom, and many consider it the funda- 
mental element of matter, which would thus be only 
an aggregation of electrons. 

Of its inmost structure we can say nothing. It is 
not giving a very certain explanation to assure us 
that it is constituted by a vortex of the ether com- 
parable to a gyrostat. Its dimensions in any case 
should be extraordinarily small, but can it be con- 
sidered indivisible, which would imply that it pos- 
sessed an infinite rigidity ? May it not be itself of 
a structure as complicated as that now attributed 
to the atom, and may it not, like the latter, form 
a veritable planetary system ? In the infinity of 
worlds, magnitude and minuteness have only a 
relative value. 

What appears to us most likely in the present 
state of our knowledge is that under the name of 
electricity are confused extremely different things, 
having the one common quality of finally producing 
certain electric phenomena. This is an idea I have 
already several times dwelt on. But we have no 
more right to call electricity everything which 
produces electricity than we have to call heat all 
causes capable of generating heat. 





§ I. Former Ideas on the Structure of Atoms. 

Before setting forth the current ideas relating to 
the constitution of matter, I will briefly refer to those 
on which science has lived till now. 

According to ideas which are still classical, matter 
is composed of small indivisible elements termed 
atoms. As these appear to persist in spite of all the 
transformations of bodies, it is supposed that they are 
indestructible. The molecules of bodies, the smallest 
particles subsisting which exhibit the properties of 
these bodies, are composed of a small number of 

This fundamental notion has existed for over 
2000 years. The great Roman poet, Lucretius, has 
set it forth in the following terms, which modern 
books do little more than reproduce : — 



" Bodies are not annihilated when they disappear from our 
view. Nature forms new beings with their remains. It is only 
by the death of some that it grants life to others. The elements 
are unalterable and indestructible, . . . The principles of 
matter, the elements of the great whole are solid and eternal: 
no foreign action can change them. The atom is the smallest 
body in nature ... it represents the last term of division. 
There therefore exist in nature corpuscules of unchangeable 
essence. . . . Their various combinations change the essence 
of bodies." 

Down to the last few years nothing had been 
added to the above except a few hypotheses on the 
structure of atoms. Newton regarded them as hard 
bodies incapable of deformation. Lord Kelvin (when 
Sir W. Thomson), harking back to the ideas of 
Descartes, supposed them to be constituted by 
vortices analogous" to those which can be formed by 
striking the bottom of a rectangular box filled with 
smoke, the upper side of which is pierced with a 
hole. This causes vortices to issue in the form of a 
ring composed of gaseous threads revolving round 
the meridians of the ring. The ring is displaced 
as a whole and is not destroyed by the contact 
of other rings. All these vortices oifer permanent 
oscillations and vibrations, the intensity and frequency 
of which are modifiable by various influences such as 
that of heat. 

It was largely on the old hypothesis of atoms that 
the theory termed atomic was founded during the last 
century. It was first supposed that all bodies brought 
to the gaseous state contain the same number of mole- 
cules in the same volume. Their weight, volume 
for volume, being supposed to be proportional to that 
of their atoms, it is possible, by simply weighing 
the body in a state of vapour, to ascertain what is 


called its molecular weight, from which is deduced, 
by a process of analysis that there is no need to show 
here, what is conventionally designated by the name 
of its atomic weight. It is compared with that of 
hydrogen taken as unity. 

§ 2. Current Ideas on the Constitution of Matter. 

It is very difficult to set forth the current ideas on 
the constitution of matter, for they are still in course 
of formation. ' We are in the midst of a period of 
anarchy, where we see the former theories vanishing 
and those springing up which will serve to build up 
the science of to-morrow. 

The scholars who follow, in . the reviews and 
scientific memoirs published abroad, the experiments 
and discussions to which are appended the names of 
the most eminent physicists, witness a curious spec- 
tacle. They see disappearing, day by day, fundamen- 
tal conceptions of science which seemed established 
solidly enough to last for ever. It is a regular 
revolution which is now in course of accomplish- 

The interpretations which flow from the facts 
recently discovered entirely upset the very bases 
of physics and chemistry, and seem destined to 
change all our conceptions of the universe. Our 
highest official teaching is, in France, too exclusively 
busy in seeing that the examination manuals are duly 
conned and is too hostile to general ideas to concern 
itself about this prodigious movement. The new 
philosophy of the sciences now coming to light has 
no interest for it. 


The scientific revolution now going on seems 
rapid, but this rapidity is much more apparent than 
real. The transformation of present ideas on the 
constitution of matter, which seems to have taken 
only a few years, was prepared, in reality, by a 
century of researches. 

Scientific ideas, in fact, only change with extreme 
slowness, and when they seem to be abruptly 
modified, it is always noted that this trans- 
formation is the consequence of a subterranean 
evolution which has taken long years to accom- 

Five fundamental discoveries form the bases on 
whicli have been slowly built up the new ideas 
relating to the constitution of matter. They are — 
1st, the facts revealed by the study of electrolytic 
dissociation ; 2nd, the discoverv of the cathode rays ; 
3rd, that of the X rays ; 4th, that of the bodies called 
radio-active, such as uranium and radium ; 5th, the 
demonstration that radio-activity does not belong 
exclusively to certain bodies and constitutes a general 
property of matter. 

The oldest of these discoveries, since, in fact, 
it goes back to Davy — that is to say, to the 
beginning of the last century — is that of the dis- 
sociation of chemical compounds by an electric 
current. Various physicists, notably Faraday, later 
completed its study. It hag led in succession 
to the theory of atomic electricity and to the pre- 
ponderating influence which the electric elements 
have in chemical reactions and the properties of 

The second of the discoveries mentioned above 
gave a glimmering idea that there might perhaps 


exist a condition of matter different to th6se 
already known; but this idea remained without 
any influence till Roentgen, examining more closely 
those Crookes' tubes which physicists had been 
handling for twenty years without seeing anything 
in them, remarked that they gave out peculiar 
rays absolutely different to everything known, 
to which he gave the name of X rays. An un- 
foreseen fact, absolutely new, and without any 
kind of analogy to known phenomena, thus burst 
into science. 

The discovery of the radio-activity of uranium, 
later of that of radium, and finally of the universal 
radio-activity of matter, very closely followed that of 
the X rays. The link which connected all these 
phenomena, apparently so dissimilar, was not at first 
seen. It was established by my researches that they 
formed but one thing. 

Long before these last discoveries, it was well known • 
that electricity played an important part in chemical 
reactions, but it was believed to be simply super- 
posed on the material molecules. By the discovery 
of electrolysis, Faraday had shown that the mole- 
cules of compound bodies carry a charge of neutral 
electricity of a definite and constant amount which 
is dissociated when solutions of metallic salts are 
traversed by an electric current. The molecules 
of bodies then came to be considered as com- 
posed of two elements, a material particle and 
an electric charge combined with it or superposed 
upon it. 

The ideas most commonly accepted before the 
recent discoveries are well expressed in the following 
passage from a work published a few years ago by 


Dr. Nernst, Professor of Chemistry at the University 
of Gottingen : — 

" The ions are a kind of chemical combination between the 
elements or radicals and electric charges . . . the combination 
between matter and electricity is subject to the same laws as the 
combinations between different matters (laws of definite propor- 
tions, laws of multiple proportions). ... If we suppose the 
electric fluid to be continuous, the laws of electro-chemistry 
seem inexplicable; if, on the contrary, we suppose the quantity 
of electricity to be composed of particles of invariable size, the 
foregoing laws are evidently a consequence thereof. In the 
chemical theory of electricity^ over and above the known elements 
there should be two others: the positive and the negative 

In this phase of the evolution of ideas, the 
positive electron and the negative electron were 
simply two .new substances to be added to the 
list of simple bodies and capable of combining 
with them. The old idea of a material atom still 

In the present period of evolution there is a 
tendency to go much farther. After asking 
themselves whether this material support of the 
electron was really necessary, several physicists 
have arrived at the conclusion that it is not so 
at all. They reject it entirely, and consider the 
atom to be solely constituted by an aggregate 
of electric particles without other elements. These 
particles can be dissociated into positive and 
negative ions, according to the mechanism ex- 
plained above. 

This was a gigantic step, and it is far from being 
one which all physicists have yet taken. A great 
uncertainty still dominates their ideas and their 


language. For the majority of them the material 
support remains necessary, and electric particles — 
that is to say, electrons — are mingled with or super- 
posed upon material atoms. These electrons, still 
according to them, circulate through conducting 
bodies, such as metals, with a velocity of the same 
order as that of light, by some mechanism totally 

To the partisans of the exclusively electrical 
structure of matter the atom is composed solely 
of electric vortices. Round a small number of 
positive elements there are supposed to revolve 
negative electrons, not less than a thousand in 
number, and often more. Together they form the 
atom, which would thus be a kind of miniature 
solar system. " The atom of matter," writes 
Larmor, "is composed of electrons, and nothing 

In its ordinary form the atom would be electric- 
ally neutral. It would become positive or negative 
only when freed from electrons of the contrary sign, 
as is done in electrolysis. All chemical actions would 
be due to the loss or gain of electrons. If, instead of 
being in a state of rapid motion, the electrons were 
in repose, they would precipitate themselves on each 
other, but the velocity by which they are animated 
causes their centrifugal force to balance their reci- 
procal attraction. When the speed of rotation is 
reduced from any cause whatever, such as a loss of 
kinetic energy due to the radiation of electrons into 
the ether, the attraction may gain the upper hand, 
and the electrons tend to unite; if it is, on the other 
hand, the centrifugal force which gains the day, they 

' ^ther atid Matter ^ p. 337.— F. L. 


escape into space, as is verified in radio-active 

The atom, and consequently matter, is therefore 
in stable equilibrium, thanks only to the movements 
of the elements which compose it. These elements 
may be compared to a top, which fights against 
gravity as long as the kinetic energy due to its 
rotation exceeds a certain value. If it falls below 
this value, the top loses its equilibrium and falls 
to the ground. But the movements of atomic 
elements are far more complicated than those 
which have just been supposed. Not only are 
they dependent on one another, but they are also 
connected with the ether by their lines of force, 
and in reality only seem to be nuclei of condensation 
in the ether. 

Such is, in broad outline, the current state of 
the ideas in course of formation as to the con- 
stitution of the atoms of which matter is formed. 
These ideas can very well be reconciled with 
those I have endeavoured to establish in this 
work, according to which the atom is a colossal 
reservoir of energy condensed in the form already 

Whatever may be the future of these theories 
it may already be positively asserted that the 
ancient chemical atom, formerly considered so 
simple, is complicated in the extreme. It appears 
more and more as a sort of sidereal system having 
one or more suns and planets gravitating round 
it with immense velocity. From the structure 
of this system are derived the properties of the 
various atoms, but their fundamental elements 
seem to be identical. 



§ 3. Magnitude of the Elements of which Matter is 


The molecules of bodies, and a fortiori, the atoms, 
are extremely small. The most minute microbes 
are enormous colossi compared with the primitive 
elements of matter : yet various considerations have 
enabled their size to be estimated. They give 
figures which no longer appeal to the mind for the 
reason that infinitely small figures are as difficult to 
picture to oneself as infinitely large ones. But it is 
owing to the extreme smallness of the elements of 
which atoms are formed that matter in course of 
dissociation can emit in permanent fashion and 
without appreciably losing weight, a veritable cloud 
of particles. 

I have spoken in a former chapter of the millions 
of corpuscles per second which one gramme of a , 
radio-active body can emit for centuries. Such 
figures always provoke a certain amount of mistrust 
because we cannot succeed in representing to our- 
selves the extraordinary minuteness of the elements 
of matter. The mistrust disappears when one 
notes that very ordinary substances are capable, 
without undergoing any dissociation, of being for 
years the seat of an emission of abundant particles 
easily verified by the sense of smell, without this 
erhission being discoverable by the most sensitive 

M. Berthelot has made on this subject some 
interesting researches.^ He has endeavoured to 
determine the loss of weight undergone by very 

^ Comptes Retidus cie VAcademie des Sciences ^ 21st May 1904. 


odoriferous though slightly volatile bodies. The 
sense of smell is infinitely superior in sensitive- 
ness to that of the balance, since in the case of 
certain substances such as iodoform, the presence, 
according to M. Berthelot, of the hundredth of 
a millionth of a milligramme can be easily revealed 
by it. 

His researches have been made with this substance, 
and he has arrived at the conclusion that one gramme 
of iodoform only loses the hundredth of a milli- 
gramme of its weight in a year — that is to say, one 
milligramme in a hundred years, though continuously 
emitting a flood of odoriferous particles in all 
directions. M. Berthelot adds, that if, instead of 
iodoform, musk were used, the weight lost would 
be very much smaller, " a thousand times perhaps," 
which would make 100,000 years for the loss of one 
milligramme. The same scholar also remarks, in a 
later work, " that there is hardly any metallic or 
other body which does not manifest, especially on 
friction, odours of its own," which is simply saying 
that all bodies slowly evaporate. 

These experiments give us an idea of the immensity 
of the number of particles which may be contained 
in an infinitesimal quantity of matter.^ 

^ Various considerations earlier than the current theories long since 
led to the attribution of an extreme smallness to the molecules of 
bodies. It has been calculated that it required 600 to 700 millions 
of bacteria to make up the weight of i milligramme. Certain of these 
bacteria give birth in 24 hours to 16 million germ^. Professor 
M'Kendrick points out that an organic germ necessarily contains 
an immense number of molecules since it must comprise the hereditary 
characteristics of a long line of ancestors. He mentions spores which 
are ^jflz^ of a millimetre in diameter, and there are probably some 
still less which we are unable to see, as the action of filtered solutions 
in which the microscope reveals nothing would tend to prove. 


From various experiments, of which the most 
recent authors, Rutherford, Thomson, etc., have 
accepted the results, i cubic millimetre of hydrogen 
would contain 36,000 billions of molecules. These 
are figures the magnitude of which can only be 
understood by transforming them into units easy to 
interpret. An idea of their enormous magnitude will 
be obtained by finding out the dimensions of a 
reservoir capable of containing a similar number of 
cubic grains of sand having each a face or side of 
one millimetre. The above quantity of grains of 
sand could only be enclosed in a parallelepipedal 
reservoir with a base of 100 metres on each of its 
faces and a height of 3,600 metres. These last 
figures would have to be much increased if we 
wished to represent the quantity of particles which 
one cubic millimetre of hydrogen would yield on 
the dissociation of its atoms. 

§ 4. The Forces which maintain the Molecular Edifices. 

We have seen that matter is constituted by the 
union of very complicated structural elements termed 
molecules and atoms. We are compelled to suppose 
that these elements are not in contact; otherwise 
bodies could neither dilate, nor contract, nor change 
their state. We are likewise obliged to suppose 
that those particles are animated by permanent 
gyratory movements. The variation of these move- 
ments can alone explain, in fact, the absorption 

According to Wismann, a blood corpuscle with a dimension of about 
tAo of * millimetre, would contain 3,625 millions of particles. 
The head of a spermatozoon, sufHcient for the fecundation of an egg 
and with a diameter of v^ of a millimetre, would contain 25,000 
million '* organic molecules," each composed of several atoms. 


and the expenditure of energy which are noticed in 
the building up and the destruction of chemical 

We ought, therefore, to picture to ourselves any 
body whatever, such as a block of steel or a rigid 
fragment of rock, as being composed of isolated 
elements in motion but never in contact. The 
atoms of which each molecule is formed themselves 
contain thousands of elements which describe round 
one or more centres, curves as regular as those of the 
celestial bodies. 

What are the forces which keep together the 
particles of which matter is formed and prevent it 
from falling into dust ? The existence of these forces 
is evident, but their nature remains totally unknown. 
The terms cohesion and affinity which are applied to 
them tell us nothing. Observation only reveals 
that the elements of matter exercise attraction 
and repulsion. We can, however, add to this 
brief statement that the atom being an enormous 
reservoir of forces, it may be supposed, as I have 
already remarked in another chapter, that cohesion 
and affinity are manifestations of intra-atomic energy. 

The stability of the molecular edifices bound to- 
gether by cohesion is generally fairly great. It is, 
however, not enough to prevent chemistry from 
modifying or destroying it by various means, notably 
by heat. That is why it is possible to liquefy bodies, 
to reduce them to vapour, and to decompose them. 
The stability of the atomic edifices, of which the mole- 
cules are formed, is, on the contrary, so great that 
it was deemed right to declare, after the experience 
of centuries, that the atom was unchangeable and 



The cohesion which keeps together the elements of 
bodies manifests itself by the mutual attraction and 
repulsion of the molecules; and the magnitude 
of the forces producing cohesion is measured by 
the effort we are compelled to make in order to 
change the form of a body. It resumes its primi- 
tive state when the action on it ceases, which 
fact proves the existence in the bosom of matter of 
forces of attraction. It resists the attempt to com- 
press it, which demonstrates the existence of forces 
of repulsion when the molecules come within a 
certain distance of each other. 

The attractions and repulsions by which cohesion 
is manifested are intense, but their radius of activity 
is extremely restricted. They cannot exercise any 
action at a distance, as does, for instance, gravita- 
tion. To nullify them we only require to separate 
the molecules of the bodies by heat. If the force of 
cohesion is abolished, the most rigid body is instantly 
transformed into liquid or vapour. 

Outside the attractions and repulsions which 
operate between the particles of the same body, 
there are others produced between the particles of 
different bodies which vary according to their nature. 
We describe them under the general term of affinity; 
and it is they which determine the majority of 
chemical reactions. 

The attractions and repulsions resulting from 
affinity engage the atoms in new combinations, or 
allow us to separate them from those combinations. 
Chemical reactions are only the destructions and 
restorations of equilibrium due to the affinities 
of the bodies present. One knows, by the effects 
of explosives, the power of the actions that 


affinity can produce when certain equilibria are dis- 

It is from the manner in which the atoms are 
grouped by the energy of affinity that the molecular 
edifices result. They may be very unstable, and 
then the least stimulus, a shock or even the touch of 
a feather, suffice to destroy them. Such is the case 
with fulminate of mercury, iodide of nitrogen, and 
several other explosives. The edifice may, on the 
other hand, be so solid that it is destroyed with diffi- 
culty. Such are those organic salts of arsenic, like 
cacodylate of soda, wherein the molecule is so stable 
that no reagent can discover the quantity, enormous 
though it be, of atoms of arsenic which it contains. 
Aqua regia, fuming nitric acid, and chromic acid are 
without action on the molecular edifice; it is a 
strongly built fortress. 

§ 5. The Attractions and Repulsions of Isolated Material 
Molecules and the Forms of Equilibrium resulting 
from them. 

The energies of affinity and cohesion are therefore 
manifested by attractions and repulsions. We have 
already seen that it is by these two forms of move- 
ment — whether in the case of material or of electric 
particles — that phenomena generally manifest them- 
selves. This is why the study of them has 
always held a preponderating place in science; 
and many physicists still reduce the phenomena of 
the universe to the study of the attractions and 
repulsions of molecules subjected to the laws 
of mechanics.. **A11 terrestrial phenomena," said 
Laplace, " depend on molecular attractions, as 



celestial phenomena depend on universal gravitation." 
Nowadays, however, it seems probable that the affairs 
of nature are more complicated. If attractions and 
repulsions appear to play so great a part, it is because 
of all the effects which forces can produce, these 
movements are the most easily accessible to us. 

The equilibria determined by the attractions and 
repulsions which are born in the bosom of solid 
bodies, are discernible with difficulty, but we can 
render them visible by isolating their particles. The 
method is easy, since it only consists in dissolving the 
solids in some suitable liquid. The molecules are 
then nearly as free as if the body were transformed 
into gas, and it is easy to observe the effects of their 
mutual attractions and repulsions. It is well known, 
moreover, that the molecules of a dissolved body 
move within the solvent and develop there the same 
pressure as if they were converted into gas in the 
same space. 

Such attractions exercised bv molecules in a 
free state are of daily observation. To them are 
due the forms taken by a drop of liquid when it 
clings to the extremity of a glass rod. They are 
the origin of what has been called the surface 
tension of liquids, a tension in virtue of w^hich a 
surface behaves as if it were composed of a stretched 
membrane. All attractions and repulsions can act 
only at a certain distance. As is known, the name 
of field of force is given to the space in which they 
are exercised, and that of lines of force to the direc- 
tions in which are produced the attracting and 
repelling effects. 

It is in the phenomena called osmotic that mole- 
cular attractions and repulsions are most clearly 


shown. When water is gently poured into an 
aqueous solution of a salt such as sulphate of copper, 
we notice by the simple difference of colour that the 
liquids are at first separate, but we soon see the mole- 
cules of the dissolved salt diffuse themselves through 
the supervening liquid. There consequently exists 
in them a force which enables them to overcome 
the force of gravity. This force of diffusion is the 
.consequence of the reciprocal attraction of the 
particles of water and of the dissolved salt. It has 
received the name of osmotic pressure or tension. 

Fit-.. 28.1 Fig. 29. 

Repulsions and allraclions of mulecules in a liquid. 

All substances which possess the property of dis- 
solving in a liquid attract the solvent, and conversely 
are attracted by it. Lime placed in a vessel rapidly 
attracts the vapour of water in the atmosphere, and 
increases in volume to the extent of breaking the 

Osmotic attractions are very energetic. In the 
cells of plants they can make equilibrium to pres- 
* The ]>liolo(;ta|ilis 18 to ,52 were taken tiy Piofessor Stephane LeJuc. 


sures of i6o atmospheres, and even more according 
to some authors- They are rarely less than ten 


Photographs of artificial cells leiultinjj fiom molecular 
IS and repulsiuns in a liquid. 


Although the magnitude of osmotic pressure is con- 
siderable, 342 grammes of sugar dissolved in a litre of 
water exercising a pressure of 22 atmospheres, this 
pressure does not manifest itself on the walls of the 
vessel, because the solvent opposes resistance to the 
movement of the molecules. To measure it, the 
substances present must be separated by a partition 

impermeable to one of them. Such partitions are 
called for this reason semi -permeable. It might be 
more correct, perhaps, to say unequally permeable. 
In the case of plant cells these partitions are formed 
■ by the walls of the cells. 

In osmotic phenomena there are always produced 
two currents in a converse direction, called exosmose 


and endosmose, of which one may overcome the other. 
These simple molecular attractions and repulsions 
acting in the bosom of liquids govern a great number 
of vital phenomena, and are, perhaps, one of the most 
important causes of the formation of living beings. 
" Osmotic pressure," says Van't Hoff, " is a funda- 
mental factor in the various vital functions of animals 
and vegetables. According to Vries, it is this which 
regulates the growth of plants; and, according to 
Massart, it governs the life of pathogenic germs." 

As the molecules existing in the midst of a liquid 
are able to attract or repel each other at a distance, 
they are necessarily surrounded by a field of force — 
that is, a region in which their action is exercised. 
By utilizing the attractions and repulsions of the free 
molecules in a liquid, M. Leduc has succeeded in 
creating geometrical forms quite analogous to those 
of the cells of living beings. According to the 
mixtures employed, he has been able to bring before 
us particles which attract and repel each other, like 
electric atoms. By spreading over a glass plate a 
solution of nitrate of potassium, on which are poured, 
at two centimetres from each other, two drops of 
Indian ink, two poles are obtained whose lines of 
force repel each other. To obtain two poles of 
contrary sign, whose lines of force, consequently, 
attract each other, a crystal of nitrate of potassium 
and a drop of defibrinated blood are placed at a 
distance of two centimetres from each other in a 
dilute solution of the salt mentioned above. By 
uniting several drops able to produce poles of the 
same sign, polyhedra are obtained with the appear- 
ance of the cells of living beings (Fig. 32). If, finally, 
a salt be crystallized in a colloidal solution — gelatine, 


for instance — the field of force of crystallization being 
able to act in the contrary direction to the osmotic 
attractions, the form of the crystal becomes altered. 
These researches cast a strong light on the origin of 
the fundamental phenomena of life. 

The above ideas on the constitution of matter 
may be summed up as follows: — As soon as we 
lift the veil of appearances, matter, so inert in its 
outward aspect, is seen to possess an extremely 
complicated organization and an intense life. Its 
primary element, the atom, is a miniature solar 
system composed of particles revolving round one 
another without touching and incessantly pursuing 
their eternal course under the influence of the forces 
which direct them. Were these forces to cease for 
a single minute, the world and all its inhabitants 
would be instantly reduced to an invisible dust. 

On these prodigiously complicated equilibria of 
intra-atomic life are superposed, by reason of the 
association of atoms, other equilibria which com- 
plicate them further. Mysterious laws known solely 
by some of their effects, intervene to build with the 
atoms, the material edifices of which worlds are 
formed. Relatively very simple throughout the 
mineral kingdom, these edifices gradually become 
complicated, as we shall now show, and have finally, 
after the slow accumulations of ages, generated 
those extremely mobile chemical associations which 
constitute living beings. 



§ I. Mobility and Sensibility of Matter. 

We have now arrived at that phase of the history of 
atoms where, under the influence of unknown causes 
of which we can only note the effects, the atoms 
have finally formed the different compounds which 
constitute our globe and the living beings upon it. 
Matter is born and will persist for a long succession 
of ages. 

It persists with different characteristics of which 
the most distinctly apparent is the stability of its 
elements. They serve to construct the chemical 
edifices of which the form readily varies but of 
which the mass remains practically invariable 
throughout all changes. These chemical edifices 
formed by atomic combinations, appear to be firmly 
fixed, but are, in reality, of very great mobility. 
The least variations of the medium — temperature, 
pressure, etc. — instantaneously modify the move- 
ments of the component elements of matter. 

The fact is, that a body as rigid in appearance 
as a block of steel, represents simply a state of 
equilibrium between its own internal energy and 
the external energies, heat, pressure, etc., which 



surround it. Matter yields to the influence of these 
last as an elastic thread obeys the pull exercised 
upon it, but regains its form — if the pull has not been 
too great — as soon as it ceases. 

The mobility of the elements of matter is one 
of its most easily observed characteristics, since it 
suffices to bring the hand near the bulb of a 
thermometer to see the column of liquid immediately 
displaced. Its molecules consequently are separated 
by the influence of slight heat. When we place 
our hand near a block of metal, the movement of 
its molecules are likewise modified, but so slightly 
that it is not perceptible to our senses, and this 
is why matter appears to us to possess but little 
mobility. ^ 

The general belief in its stability seen)s to be 
confirmed, moreover, by observing that in order to 
subject a body to considerable modifications, to melt 
it or change it into vapour, for instance, very powerful 
means- are required. Sufficiently exact methods of 
investigation show, on the contrary, that not only 
is matter of an extreme mobility, but is further 
endowed with an unconscious sensibility which 
cannot be approached by the conscious sensibility 
of any living being. 

It is known that physiologists measure the sensi- 
bility of a being by the degree of excitement necessary 
to produce in it a reaction. It is considered very 
sensitive when it reacts under very slight excitants. 
Applying to mere matter a similar means of pro- 
cedure, we note that the substance most rigid and 
least sensitive in appearance is, on the contrary, 
of an unexpected sensibility. The matter of the 
bolometer, reduced by final analysis to a thin 


platinum wire, is so sensitive that it reacts — by a 
variation of electric conductivity — when struck by 
a ray of light of such feeble intensity as to produce 
a rise in temperature of only the hundred millionth 
of a degree. 

With recent progress in the means of examination 
this extreme sensitiveness of nature becomes more 
and more manifest. Mr. H. Steele has found that 
it is sufficient to touch an iron wire slightly with the 
finger for it to become immediately the seat of an 
electric current. It is known that hundreds of miles 
away the Hertzian waves greatly modify the state of 
the metals with which they come in contact, since 
they change in enormous proportion their electric 
c6nductivity. It is on this phenoinenon that ^yireless 
telegraphy is based. 

The extraordinary sensibility of matter which has 
enabled the bolometer to be created and wireless 
telegraphy to be discovered, is utilized in other 
instruments employed in industry; such as, for 
instance, the telegraphone of Poulsen, which enables 
spoken words to be preserved and reproduced by the 
changes of magnetism brought about in the surface 
of a steel band moving between the poles of an 
electro-magnet to which a microphone is attached. 
When you speak into the membrane of this last, the 
minute fluctuations of the current in the microphonic 
circuit cause variations of magnetism in the mole- 
cules of the steel ribbon of which the metal retains 
the trace. These variations permit us to reproduce 
the speech at will by passing the same band between 
the poles of an electro-magnet put in circuit with a 

This sensibility of matter, so contrary to what 


popular observation seems to indicate, is becoming 
more and more familiar to physicists. This is why 
such an expression as "the life of matter," utterly 
meaningless twenty-five years ago, has come into 
common use. The study of mere matter yields ever- 
increasing proofs that it has properties which were 
formerly deemed the exclusive appanage of living 
beings. By taking as a basis this fact " that the most 
general and most delicate sign in life is the electric 
response," Mr. Bose has proved that this electric 
response " considered generally as the effect of an 
unknown vital force" exists in matter. And he 
shows by ingenious experiments " the fatigue " of 
metals and its disappearance after rest, and the 
action on these same metals of excitants, of depress- 
ants, and of poisons. 

We must not be too much astonished at finding 
in matter properties which once seemed to belong 
solely to living beings, and it would be useless to 
seek therein a too simple explanation of the still 
impenetrable mystery of life. The analogies dis- 
covered are, it is likely, due to the fact that nature 
does not greatly vary her procedure and constructs 
all beings, from mineral to man, with similar 
materials, whence they are endowed with common 
properties. It always applies the fundamental prin- 
ciple of least action, which would suffice by itself to 
establish the fundamental equations of mechanics. 
It consists, as we know, in the enunciation, so simple 
and of such deep import, that of all roads which lead 
from one situation to another, a material molecule 
under the influence of a force can take but one 
direction, namely, the one which demands the least 
effort. It will probably be seen one day that this 


principle is not only applicable to mechanics but 
also to biology. It is perhaps also the secret cause 
of the laws of continuity observed in many pheno- 

§ 2. Variation of the Equilibria of Matter under the 

Influence of the Medium. 

Matter is, then, like all beings, strictly dependent 
on the medium in which it finds itself, and is 
modified by the slightest changes in this medium. 
So long as these changes do not exceed certain limits, 
the velocity and amplitude of the movements of the 
material molecules are modified without any change 
in their relative position. If these limits are ex- 
ceeded, the equilibria of matter are destroyed or 
transformed. The majority of chemical reactions 
show us such transformations. 

But in every way matter is so mobile and so 
sensitive that the most insignificant changes in the 
medium — for instance, a rise or fall in temperature 
of the millionth of a degree — produce modifications 
which our instruments allow us to note. 

Matter, as we know it, only represents, as I have 
before said, a state of equilibrium, a relation between 
the internal forces it contains and the external forces 
which act upon them. The last cannot be modified 
without a similar change in the first, as one pan of a 
balance cannot be touched without causing the other 
to oscillate. It may therefore be said, in mathe- 
matical language, that the properties of matter are 
a function of several variable factors, especially 
temperature and pressure. 

These various influences are capable of acting 


separately, but they may also act in combination. 
Thus there exists a temperature — variable for each 
body — ^called critical, above which no body can exist 
in a liquid state. It then immediately becomes 
gaseous and remains so whatever pressure may be 
brought to bear on it. If water is heated in a closed 
tube, a time arrives when, suddenly, it transforms 
itself entirely into a gas so invisible that the tube 
seems totally empty. For a long time many gases 
could not be liquefied,^ precisely because it was not 
known that the action of pressure was null if the gas 
had not been first lowered below its critical point. 
Carbonic acid is very easily liquefied by pressure at a 
temperature below 31° C. Above that temperature 
no pressure can bring it to a liquid state. 

Matter must therefore be considered as a most 
mobile thing, very unstable in equilibrium, and impos- 
sible to be conceived of apart from its surroundings. 
It possesses no independent property beyond its 
inertia, from which it derives the constancy of its 
mass. This property is absolutely the only one 
which no change of surroundings, pressure, tem- 
perature, etc., can alter. Take aw^ay from matter 
its inertia, and one does not see how it is possible to 
define so changeable a thing. 

Notwithstanding the extreme mobility of matter/ 
the world, however, seems very stable. It is so, in 
fact, but simply because, in its present state of 
evolution, the medium in which it is wrapped varies 
within rather narrow limits. The apparent con- 
stancy of the properties of matter results solely 

^ Since ihe experiments of Sir James Dewar, even the lightest of 
gases, hydrogen, has been liquefied by the combined effect of intense 
cold and pressure. Only helium now resists. — F. L. 


from the present constancy of the medium in which 
it is plunged. 

This notion of the influence of the medium, rather 
neglected by the old chemists, has finally acquired 
great importance, since it has been proved that many 
reactions depend upon it, and vary in very different 
directions, according to the alterations, sometimes 
very slight, of temperature or of pressure. When 
the differences are considerable, many reactions 
are found to be entirely transformed, or to become 
impossible. If one could only examine substances at 
certain temperatures, one would consider them very 
different from the same substances observed at 
ordinary temperatures. At the temperature of liquid 
air, phosphorus loses its violent affinity for oxygen, 
and is without action upon it; sulphuric acid, which 
generally acts so markedly on litmus paper, no longer 
turns it red. At a high temperature we see, on the 
other hand, new affinities non-existent at ordinary 
temperatures come to light. Nitrogen and carbon, 
which combine with no other bodies at a low tem- 
perature, easily combine with several at 3000 
degrees, and form bodies hitherto unknown — 
carbide of calcium, for example. Oxygen, which 
generally has no action on the diamond, acquires so 
energetic an affinity for this body at a high tempera- 
ture that it combines with it and becomes incan- 
descent. Magnesium has a rather mild affinity for 
oxygen, but at a sufficiently high temperature its 
affinity for it reaches such a point that, when 
plunged into an atmosphere of carbonic acid, it 
decomposes it, seizes upon its oxygen and burns 
continuously when lighted. 

Thus, then, the elements of matter are in in- 


cessant motion: a block of lead, a rock, a chain of 
mountains have but an apparent immobility. They 
are subject to all the variations of the medium and 
are constantly modifying their equilibria to corre- 
spond to it. Nature knows no rest. If repose exists 
anywhere, it is neither in the world we inhabit nor 
in the beings on its surface; nor is it even existent in 
death, which only substitutes for certain momentary 
equilibria of atoms other equilibria whose duration 
will be as ephemeral. 



§ I. The Gaseous, Liquid, and Solid States. 

According to the external forces to which it is 
subjected, matter assumes three states, which have 
been called the solid, liquid, and gaseous. Yet the 
most recent researches have clearly proved that there 
exists no wide separation between them. The con- 
tinuity of the liquid and gaseous states has been 
put in evidence by the researches of Van der Waals, 
and the continuity of the liquid and solid states 
by different other experimenters. Under sufficient 
pressure, solids behave like liquids, their molecules 
slide one over the other, and a solid metal at length 
flows like a liquid. " The laws of hydrostatics and 
hydrodynamics," says Spring, "are applicable to 
solids subjected to strong pressures." This property 
of the hardest bodies of behaving like liquids under 
certain pressures has been utilized commercially in 
America for the manufacture of tools from blocks of 
steel subjected to sufficient pressure without the need 
of raising the temperature. Yet this metal may be 
regarded as the type of substances hardly malleable. 

The crystalline state itself cannot establish a very 
clear separation between the solid and liquid states. 
There exist, as Lehmann has shown, semi-liquid 
crystals, and I myself have found a means of 



preparing crystals of a pasty consistency.^ We 
have seen above that liquids, while remaining liquids, 
can assume geometrical forms akin to the crystalline 
state, and certain optical processes allow us to 
reveal their existence. 

In a general way, however, the crystalline state 
constitutes, as we shall see, a very peculiar stage of 
matter which gives it an individuality of its own, and 
approaches, from some points of view, that of living 

§ 2. The Crystalline State of Matter — Life of Crystals. 

Among the unknown forces of which we only per- 
ceive the existence by a few of their effects, are found 
those which compel the molecules of bodies to take 
strictly geometrical forms bearing the name of 
crystals. All solid bodies have a tendency towards 
the crystalline form.^ The geometrical equilibria 
from which these forms result, give a kind of 
individuality to the molecules of matter. Matter 
individualizes them in the same sense that the 
living being does — by incorporating the elements 
borrowed from the medium with itself. 

There is nothing out of the way in this expression — 
the individualization of matter — when applied to its 
transformation into geometrical bodies. The mineral 

^ Simply by holding a strip of magnesium with a long pair of tongs 
for some minutes in boiling mercury. Qn cooling, the mixture assumes 
the form of crystalline flakes, the crystals of which have the con- 
sistency of butter, and consequently lose their shape under the pressure 
of the finger. 

' Professor Quincke, of Heidelberg, has lately shown that all sub- 
stances, on passing from the liquid to the solid state, assume what he 
calls a ''foam structure," or become a network of cells which may 
enclose crystals. Proc, Roy, Soc^ 21st July 1906. — F. L. 



being is characterized by its crystalline form as the 
living being is characterized by its anatomical one. 
The crystal also undergoes, like the animal or the 
plant, a progressive evolution before attaining its final 
form. Again, like the animal or the plant, the 
mutilated crystal can repair its mutilation. The 
crystal is in reality the final stage of a particular 
form of life. 

Fig. 33. Fig. 34. Fic. 35. 

Tht three phases of Ihe siiccessire fonnation of a crystal. 

{From ihe photc^apha of rrofessor Schriin.) 

Among the facts which may serve as supports to 
these considerations, must be especially quoted the 
beautiful experiments of Professor Schron on the 
successive transformations which cause material 
molecules to assume the crystalline form. The three 
principal ones are — ist, a granular phase; 2nd, a 
fibrous phase; 3rd, a homogeneous phase. They are 
represented by the three photographs here reproduced, 
which I owe to the courtesy of the scholar in ques- 


tion. In a solution about to crystallize are first 
formed globules, in the heart of which granulations 
soon appear (Fig. 33). These granulations elongate 
and take a fibrous aspect (Fig. 34), to which later 
on succeeds the homogeneous state (Fig. 35), which 
constitutes the definitive form of the crystal. The 
crystal being has then terminated its cycle. 

These laws of the formation of crystals are general, 
and can be observed in the crystals of mineral sub- 
stances as well as in those which, according to 
Schron, accompany micro-organisms. Among the 
secretions of every microbe there always appear, 
according to him, crystals characteristic of every 
species of microbe. 

These observations show that during its pre- 
crystalline period — that is to say, its infancy, the 
future crystal behaves like a living being. It repre- 
sents tissue in course of evolution. It is an organ- 
ized being undergoing a series of transformation of 
which the final stage is the crystalline form, as the 
oak is the final stage of the evolution of the acorn. 
The crystal would therefore seem to be the last phase 
of certain equilibria of matter unable to rise to the 
forms of higher life. 

Researches carried out in different directions 
confirm the above conclusions. Thus M. Cartaud 
has found that metals, polished and then attacked 
by picric acid dissolved in acetone, exhibit "a 
completely closed and microscopic network of 
cells." ''Cells and crystals show," he says, "an 
evident affiliation. Pebbles with the same crystalline 
orientations have the characteristic of possessing a 
cellular web of specific form and disposition, which 
permits a crystal to be regarded as an aggregate of 


similar cells arranged in the same way.*'^ Cellular 
structure would therefore seem to be an embryonic 
phase, and crystalline structure an adult phase. 

Far from being an exceptional state, the crystal- 
line form is, in reality, the one to which all forms 
tend, and which they attain so soon as certain con- 
ditions of the medium are realized. Salts dissolved 
in an evaporating solution, and a melted metal when 
cooled, always tend to assume the crystalline form ; 
and if we consider, as we do nowadays, that solutions 
show close analogies with gases, it may be said that 
the two most usual forms of nature are the gaseous 
and the crystalline. 

There is hardly in nature anything but the crystal 
which possesses a truly stable and definite form. An 
ordinary living being is, on the other hand, something 
extremely mobile, always changing, and only continu- 
ing to live on the condition that it dies and is re-born 
unceasingly. Its form only appears definite because 
our senses can only perceive fragrnents of things. 
The eye is not made to see everything. It picks out 
of the ocean of forms that which is accessible to it, 
and believes this artificial limit to be the real limit. 
What we know of a living being is only a part of 
its real form. It is surrounded by the vapours it 
exhales, by radiations of great wave length, which it 
is constantly emitting by reason of its temperature. 
Could our eyes see everything, a living being* would 
appear to us as a cloud with changing contours.^ 

* Cf, note on page 257 sup, — F. L. 

^ Our eyes are not sensitive to the infra-red radiations which living 
beings jire unceasingly giving out, but let us imagine a being whose 
eyes — as may be the case perhaps with nocturnal animals — are organ- 
ized so as to be able to perceive only radiations of great wave length 


Whence comes the crystal which appears in a 
solution ? What is the starting point of the trans- 
formations undergone by the molecules of this 
solution before becoming a crystal? Observation 
shows that all living beings from bacteria up to man, 
always proceed from an earlier being. Can it be 
the same with a crystal ? Is it also derived by 
affiliation from an earlier being, or is it born spon- 
taneously ? 

It seems now well proved, especially since the re- 
searches of Ostwald, that with crystals both these 
modes of generation exist. In certain fixed conditions 
of the medium — that is to say, of pressure, concen- 
tration of solutions, etc., liquids can only crystallize 
if they have first received a crystalline germ. The 
crystals thus formed may then, according to the ex- 
pression of Dastre in his great work La Vie ct la Mort, 
be considered as the posterity of an earlier crystal, 
absolutely in the same way that the bacteria 
developed in a solution represent the posterity of 
the bacteria originally introduced therein. 

There exist, however, other conditions of the 
medium in which spontaneous crystallization may 
be observed without any previous introduction of 
germs. These different conditions being known and 
being producible at will, a solution may be placed 
either in conditions allowing it to crystallize spon- 
taneously or in such that it will only crystallize after 
the introduction of suitable germs. It may therefore 

and not those of the rest of the spectrum which are to us light. 
To a being thus organized, an animal would appear in the shape of a 
mist with indistinct outlines which would be rendered visible by the 
reflection of the infra-red radiations on the water vapour surround- 
ing it. 


be said that crystals present two very distinct modes 
of reproduction — spontaneous generation and genera- 
tion by affiliation. 

This faculty of spontaneous generation, possible to 
the crystal being, is, as is well known, impossible to 
the living being. The latter is only produced by 
affiliation, and never spontaneously. However, it 
must be admitted that before being born by affilia- 
tion, the original cells of the geological periods must 
have been born without parents. ^ We are ignorant 
of the conditions which permitted matter to organize 
itself spontaneously for the first time, but nothing 
indicates that we shall always be thus ignorant. 

We therefore see the notion accentuating that the 
crystal forms a being intermediate between brute and 
living matter, and placed nearer to the latter than to 
the former. It possesses in common with living 
beings the qualities above mentioned, and in par- 
ticular something singularly resembling ancestral 
life. The crystalline germs we introduce into a 
solution in order to crystallize it seem to hint at a 
whole series of earlier lives. They recall the germs 
of living beings — that is to say, the spermatozoa 
which comprise the sum of the successive forms 
of the life of a race, and contain, notwithstanding 
their insignificant size, all the details of the successive 
transformations which the living being exhibits before 
arriving at the adult stage. 

All the facts of this order belong to the category 
of unexplained phenomena of which nature is full, 
and which become more numerous as soon as we 
penetrate into unexplored regions. The complexity 
of things seems to increase the more they are 




^ 1. Are the different Simple Bodies compounded from 

one Element ? 

When we submit the various compounds existing in 
nature to certain chemical operations, we succeed in 
separating them into elements which no reaction can 
further decompose. These irreducible elements are 
termed simple bodies, or chemical elements. From 
their combinations are formed our globe and the 
beings which inhabit it. 

The idea that all bodies supposed to be simple 
must be derived from one single element in different 
states of condensation or combination, comes so 
naturally to the mind that it was put forth directly 
chemistry was established. After having been aban- 
doned for want of proof, it was reborn when the 
recent experiments on the dissociation of matter 
seemed to show that the products resulting from the 
dissociation of the various bodies are formed of the 
same elements. 

Facts known at an early date already indicated 
that the atoms of the most dissimilar bodies possessed 
certain properties in common. The most important 
of these are the identity of the specific heat and of 
the electric charge when, instead of with like weights 



of matter, we work with quantities proportional to 
the atomic weights. 

Every one knows that the specific heat of bodies — 
that is to say, the quantity of heat, expressed in calories, 
which has to be communicated to them in order to 
raise their temperature the same number of degrees 
— varies with different bodies. It is thus that, with 
the amount of heat necessary to raise a kilogramme 
of water by 3', the temperature of a kilogramme of 
mercury can be raised by 97°. But if, instead of 
comparing equal weights of the different substances, 
weights proportional to their atomic weight are com- 
pared, it is noted that all bodies experience the 
same amount of heating from the same amount 
of heat, while electrolysis also proves that they carry 
an electric charge identical for the same atomic 
weight. To these facts, long known, are added those 
resulting from the recent researches here described, 
which show that, by the dissociation of matter, the 
like products are obtained from the most different 
bodies. It may therefore be admitted as extremely 
likely that all bodies are formed of one and the same 

But even were the demonstration of this unity of 
composition complete, it would only offer a slight 
practical interest. By chemical analysis the same 
elements are discovered in a painting by Rembrandt 
as in a public-house signboard, and it is likewise 
proved that the body of a dog and that of a man have 
the same composition. Such observations as these 
give us absolutely no knowledge of the structure of 
the bodies thus analysed. So far as atoms are con- 
cerned, what we desire to discover is the architec- 
tural laws which have enabled completely different 


edifices to be created with similar materials. Nothing 
is more probable than the fact that the atoms of 
chlorine, of* zinc, and of the diamond are composed 
of one element. But how can this element give the 
elements of the various substances such different pro- 
perties ? Of this we are so completely ignorant that 
we are unable even to formulate any hypothesis on 
the subject. 

Whatever may be the nature of the equilibria 
existing in the elements of the atoms of the various 
simple bodies, it is certain that these equilibria 
possess, in spite of their mobility, a very great 
stability, since, after the most violent chemical 
reactions, the simple bodies are always again found 
unaltered. None- of the transformations to which 
a given quantity of any element may be subjected 
modify either its nature or its weight. It is for this 
very reason that atoms have hitherto been considered 

This apparent indestructibility has always given 
great force to the belief in the invariability of 
chemical species. We shall see, however, that by 
looking a little closer into things, this argument 
loses much of its value ; for, without invoking the 
phenomenon of the dissociation of matter, we shall 
prove that the same bodies may really undergo very 
thorough transformations of their properties, which 
sometimes even suggest actual transmutations. 

§ 2. Can Simple Bodies be considered as Elements of an 

Unvarying Fixity ? 

At the beginnings of chemistry the methods of 
analysis somewhat lacked refinement and the pro- 


cesses of physical investigation, such as spectroscopy, 
were unknown. It was therefore impossible to sepa- 
rate, and consequently to acquire, a knowledge of 
any bodies save those with well defined properties. 
These bodies were too visibly different to be possibly 
confused. It was thus that arose the doctrine, anal- 
ogous to that then admitted in biology, that chemical 
species were, like the species of living beings, invari- 
able. Yet, after half a century of patient observa- 
tion, biologists have finally abandoned the idea 
of the invariability of species, while chemists still 
defend it. 

The facts discovered have shown, however, that, 
there exist between chemical species as between 
living species, transitions which cannot be disputed. 
It has had to be recognized that a good number of 
simple bodies by no means present clearly defined 
properties which allow them to be easily differentiated. 
There are many, on the contrary, so near to each other 
— that is to say, possessing qualities so much alike — 
that no chemical reaction can distinguish them ; and 
it was for this very reason that they were so long 
unknown. Almost a quarter of the simple bodies 
known — that is to say, about fifteen, so resemble 
each other in their chemical characteristics that 
without the employment of certain methods of 
physical investigation (spectrum rays, electrical 
conductivity, specific heat, etc.) they could never 
have been isolated. These bodies are those metals 
the oxides of which form what are termed the 
" rare earths." " They are only distinguished," 
say MM. Wyrouboff and Verneuil, " with but two 
or three exceptions, by their physical properties and 
are chemically identical. So much is this the case 


that no reaction has yet been found to separate 
' them, and one is reduced, in order to obtain them 
in a more or less pure state, to the empirical and 
rude process of fractionation." 

Other recently discovered facts show that the most 
marked chemical species, such as ordinary metals, 
present numerous varieties. There exists, probably, 
round each element, a whole series of varieties with 
common characteristics, which possess, however, 
properties sufficiently sui generis for them to be 
distinguished ; as is observed in living species. Silver, 
as we shall presently see, is not one single metal. 
There exist at least five or six kinds of silver, con- 
stituting very different simple bodies. It is the same 
with iron and, probably, with all the other metals. 

The earlier chemistry carefully noted the existence 
of bodies seemingly identical in nature though 
differing in properties. It termed " allotropic " these 
different states of a same body. If it did not class 
them, as independent simple bodies, it was because 
by means of various reagents they could always be 
brought back to a common state. Red phosphorus 
differs entirely from white, and the diamond differs 
no less from carbon ; but either white phosphorus or 
red can give the same compound — namely, phos- 
phoric acid. With either coal or the diamond the 
same compound can also be made — namely, carbonic 

Without these common properties we should never 
have dreamed of classing together bodies so widely 
dissimilar as the coal and the diamond, or white 
and red phosphorus. White phosphorus is one 
of the bodies most greedy for oxygen and red 
phosphorus one of the least so. White phos- 


phorus melts at 44* C, while red will not melt 
at any temperature and turns into vapour with- 
out passing through the liquid state. The first 
is one of the most poisonous bodies known, while 
the second is one of the most innocuous. Equally 
marked differences exist between the coal and the 
diamond. It is the same with certain metals which 
may occur in greatly differing forms. M. Coste has 
shown that selenium slowly cooled is a good conductor 
of electricity, for which reason he has given it the 
name of metallic selenium. Ordinary vitreoys 
selenium obtained by rapid cooling, is, on the 
contrary, an insulator, and consequently no longer 
possesses the properties of a metal. 

So long as the allotropic state was only observed 
in a very small number of bodies it was possible to 
look upon them as exceptions, but more sensitive 
methods of investigation have proved that what was 
considered exceptional constitutes, on the contrary, 
a very general law. The learned astronomer, 
Deslandres, supposes that the great differences 
observable in the spectrum of many bodies — carbon 
and nitrogen, for instance — according to the tempera- 
ture at which they occur, are due to the allotropic 
states of these bodies.^ 

Without the need of invoking the hints sup- 
plied by spectrum analysis, it is easy to note that 
the commonest and most distinguishable bodies, 
such as iron and silver, display many different 
allotropic states which allow us to class them as 
different species of the same genus. There are 
already half a dozen different kinds of iron and 
silver known which have clearly defined character- 

^ Comptes rendus de V Academic des Sciences^ 14th September 1903. 


istics, although they possess certain inactions in 
common which formerly led to their being confused. 
It is probable that with new methods of observation 
the number of these species will be greatly increased. 
Recent researches on colloidal metals, which we 
shall refer to in another chapter, even show that 
certain species of metals are capable of being so 
modified as to lose all the properties of the metal 
from which they are derived and to resetnble 
organic substances rather than metals. 

But without even glancing at these extreme cases 
of colloidal metals, and only taking the most or- 
dinary bodies, prepared by the absolutely classic 
methods, it has to be acknowledged, as we shall 
see, that the same metal can present itself in forms 
impossible to be confused. 

It is known that the heat absorbed or dis- 
engaged by the various simple bodies, in their 
combinations, is a constant quantity, represented 
by exact figures, and that it constitutes one of 
their essential characteristics. These figures, fot- 
merly considered invariable for each body, have 
served to found a special science — to wit, thermo- 

As soon as the allotropic forms of metals became 
known, these figures were taken in hand and it had 
to be acknowledged that, according to the mode of 
preparation of the metal, they might be twenty times 
higher or lower than the figures found for the same 
bodies when prepared by different methods. It 
therefore cannot be said, for a great number of the 
figures published up to now, that they are even 
roughly approximate. It was Berthelot himself, one 
of the founders of thermo-chemistry, who con- 


tributed to the verification of this fact.^ It is very 
probable that had he done so thirty years earlier, 
thermo-chemistry would never have been born. 

From the standpoint taken by me as to the varia- 
bility of chemical species, these results are of the 
greatest interest. From the standpoint of the ideas 
hitherto dominant on which thermo-chemistry was 
founded, they are plainly disastrous. M. Berthelot 
urges this by the following considerations: — 

" Such inequalities of energy as these being thus established 
by experiment, it is clear that there cannot be accorded with 
certitude to ordinary metals, nor, more generally, to elements, 
in the discussion of their reactions, the thermo-chemical values 
obtained by starting from different states. 

'* The states of silver that I have studied do not, with one 
exception, answer to the figures of + 7 cal. for the heat of for- 
mation of the oxide Ag^O, which is given in thermo-chemical 

" In the case of silver the thermo-chemical difference of the 
states of this element may rise, for one atom of silver, to 2 
calories, which makes, for the formation of oxide, with 2 atoms 
of silver (Ag O), a difference of +4 calories." 

The figures given in -the books would then be, in 

' Here, moreover, are the figures obtained for silver by M. Berthe- 
lot, according to the kind of metal employed (see the Comptes rendus, 
4th February 1901). These figures represent the heat of the solution of 
an equal weight of substance in mercury : — 

1st, Silver in thin leaves 1 + 2.03 cal. 

2nd, Silver produced by the transformation of the above metal 
heated for 20 hours at 500-550° C. in a current of oxygen: + .47 cal. 

3rd, Silver crystallized in needles, obtained by electrolysis from 
nitrate of silver dissolved in 10 parts of water: + .10 cal. 

4th, Silver precipitated from its nitrate by copper; washed and dried 
partly at the normal temperature : + 1. 10 cal. 

5th, The above silver dried at 120** C. : +.76 cal, 

6th, The above silver heated to a dark red : + .08 cal. 


the above case, wrong by nearly fifty per cent. The 
same author then asks himself whether it might not 
be the same with iron, of which so many allotropic 
forms occur. The observation is probably applic- 
able, not only to iron, but to all other bodies. 
What therefore ' is there left of all the figures 
which thermo-chemistry formerly displayed as so 
infallible ? 

There will probably remain very little, for even if 
we start from metals prepared in the same way, 
there is no certainty of starting from an identical 
body, since its simple dessication temperature per- 
mits its heat of combination to vary, and it is 
sufficient to very slightly change its physical state 
to also change its thermal properties. Faraday 
remarked, a long time ago, that 'silver, deposited on 
a plate of glass by chemical means, had a great 
refracting power and a very feeble transparence. If 
we heat the glass plate to from 250" to 300' C, the 
silver loses the greater part of its refracting power 
and acquires a great transparence. Faraday con- 
cluded from this that silver, in these two cases, must 
represent very different forms, and this prediction 
has been fully confirmed by experiment. 

At the time when the figures of thermo-chemistry 
were established, chemists could not have reasoned 
other than they did, since they were not then able to 
differentiate bodies except by reactions incapable of 
bringing to light certain dissimilarities which were, 
however, fundamental. Silver, whatever its origin, 
when treated by nitric acid, invariably yielded nitrate 
of silver of the same composition per cent., and one 
could always extract from it the same quantity of 
metallic silver. How, then, was it possible to suspect 


that there existed, in reality, metals differing from 
each other, although presenting the same appearance 
and known by the name of silver ? 

We nowadays know this because our methods of 
investigation have been perfected. When they are 
still more perfect, it is probable, as I have said before, 
that the number of chemical species derived from 
the same body will further increase. 

The foregoing facts establish this important 
general law: that simple bodies are by no means 
composed of determined elements invariable in struc- 
ture, but of elements which can be varied within 
rather wide limits. Every simple body only represents 
a type from which greatly different varieties aire 
derived. By adopting for the classification of 
metals that employed for living beings, it might be 
said that a metal like silver or iron constitutes a genus 
which includes several species. All the species of 
the same genus, the genus iron and the genus silver, 
for example, are absolutely distinct though possess- 
ing common characteristics. And if we consider 
that in the mineral world species are modified with 
some ease, since, for instance, the white phosphorus 
species may become the red phosphorus species, or 
that the silver species, capable of disengaging many 
calories in its combinations, may become a species 
which disengages a smaller number, it is allowable 
to affirm that chemical species are much more easily 
transformable than animal species. It is not a 
matter for wonder, since the organization of the 
latter is much more complicated than that of the 

Chemical species, then, are subject to variability. 
We know, on the other hand, that, given certain 


appropriate actions, atoms may undergo the beginning 
of dissociation. Is the variability of simple bodies 
limited ? May we hope, on the contrary, to succeed 
in totally transforming a simple body ? This is the 
problem which we will now proceed to examine. 




§ I. Variability of Simple Bodies, 

** It is very rare," wrote more than sixty years ago 
the celebrated chemist Dumas, "that one succeeds in 
comprehending the laws of a whole class of pheno- 
mena, by studying those whose action is displayed 
with the greatest intensity. It is generally the con- 
trary which is observed, and it is nearly always by 
the patient analysis of a slight or slow phenomenon 
that one succeeds in discovering the laws of those 
which at first escaped analysis." 

The whole history of science confirms this view. 
It was by attentively examining the oscillations of a 
hanging lampi that Galileo discovered the most im- 
portant of thte laws of mechanics. It was by a 
lengthened study pf the shadow of a hair th^^Fresnel 
built up the theories which transformed ftie science 
of optics. It was by analyzing, with rudimentary 
apparatus, minute electric phenomena that Volta, 
Ampere, and Faraday^ called forth from the void a 
science which was shortly to become one of the most 
important factors of our civilization. 

" It is certain that in the future as in the past," 
writes M. Lucien Poincare, " the most profound dis- 

* The home-made appearance of the apparatus of Faraday, now 
exhibited at the Royal Institution, must strike every visiton — F. L, 



coveries, those which will suddenly reveal regions 
entirely unknown, and open up perfectly fresh 
horizons, will be made by a few men of genius 
who will pursue in solitary meditation their stubborn 
labour, and who, to verify their boldest conceptions, 
will doubtless require only the most simple and least 
costly methods of experiment." 

Considerations such as these should always be 
borne in mind by independent seekers when they 
find themselves stopped from want of means, or by 
the indifference or hostility which most often requites 
their labours. There exists, perhaps, no physical 
phenomena which, studied with patience in all its 
aspects, will not finally reveal, thanks to very simple 
means of investigation, totally unexpected facts. 
It was thus that the attentive study of the effluves 
generated by light on the bit of metal struck by it 
was the origin of all the researches noted in this 
work, and finally led me to demonstrate how little 
foundation there was for the century-old dogma of 
the indestructibility of matter. 

The great interest of such researches, when 
stubbornly followed up, consists in constantly seeing 
new facts appear, and in never knowing into what 
unknown region one will be led. I have noticed this 
more than once during the many years devoted to 
my experiments. Undertaken with quite another 
object, they led me to study experimentally the 
question of the variability of chemical species; and if 
I give the preceding explanations, it is somewhat to 
excuse myself for having treated of a subject which 
would seem, at first sight, outside the scope of my 

From the philosophical point of view, the problem 


of the variability of chemical species is of the same 
order as that of the variability of the species of living 
organisms, which has for so long agitated science. 
Energetically denied at first, this variability of species 
has at last been accepted. The principal argument 
which led to its adoption is the extent of the variations 
to which beings can be subjected, although no one 
has ever succeeded in experimentally obtaining the 
transformation of a single species. If, therefore, we 
succeed in obtaining very great variations of some 
chemical species, the possibility of their transforma- 
tion may be admitted for reasons of the same order 
as those which have appeared convincing to 

The variability of chemical species, put in evidence 
in the preceding chapter by the simple statement of 
facts already known, needed to be first discussed in 
order to prepare the reader for the interpretation of 
the experiments I will now detail. 

To obtain the transformation of certain bodies we 
shall require no energetic means, such as high tem- 
peratures, great electric potential, or the like. I have 
already shown that matter, very resistant to mighty 
agencies, is sensitive, on the contrary, to slight 
excitants on Condition that they are appropriate. 
It is precisely for this reason that, notwithstanding 
its stability, it can be dissociated under the influence 
of slight causes, such as a feeble ray of light. 

I have already pointed out the very important part 
played by traces of a foreign substance when added 
to certain bodies. Its importance struck me as soon 
as I saw such curious properties as phosphorescence 
and such capital ones as radio-activity produced 
by the influence of such admixtures* If such import- 


ant phenomena can be created by such very simple 
means, may it not be possible, by proceeding in an 
analogous manner, to succeed in modifying all the 
fundamental properties of certain elements ? 

By fundamental properties we understand those 
apparently irreducible ones upon which chemists 
rely for their classification. Thus, the property 
possessed by aluminium of not decomposing water 
when cold and of not being oxidized at the 
ordinary temperature constitutes one of the funda- 
mental characteristics of this metal. If it can be 
compelled to oxidize when cold and to decompose 
water by simply adding to it traces of certain bodies, 
we shall evidently have the right to say that its 
fundamental properties have been modified. 

As these experiments are merely accessory, since 
they go beyond the scope of my researches, I 
have only brought them to bear on three metals — 
namely, aluminium, magnesium, and mercury. And 
as, although very simple, they necessitate certain 
technical explanations, I refer the reader for their 
detailed description to the purely experimental part 
of this work. It will there be seen that by putting 
the first two of these metals in the presence of traces 
of various substances — for example, distilled water 
which has served to wash out an- empty flask 
previously containing mercury — it becomes possible 
so to modify their characteristics that, if classified 
according to their new properties, .their places in 
the list of elements would have to be altered. There- 
after, these metals, which are generally without any 
action on water, decompose it violently; the aluminium 
instantaneously becomes oxidized in air, becoming 
covered with thick tufts which grow under one's 


eyes, and which give to a plate of polished aluminium 
the look of a jungle.^ 

Several hypotheses were put forward to explain 
these facts when presented in my name to the 
Academic des Sciences. M. Berthelot pointed out 
that two metals in the presence of each other 
might form an electric couple which might be the 
origin of the phenomena noticed, and that therefore 
it would not be the properties of metals which were 
under observation but those of their couples. This 
is evidently a very insufficient explanation. 

Other scholars have compared the metals thus trans- 
formed to alloys which, according to certain ideas 
now in vogue, are constituted by combinations in 
defined proportions, dissolved in the excess of one of 
the metals in question. But in alloys, the changes 
obtained, such as hardness, fusibility, etc., are 
especially of the physical order, and in none of 
them are observed chemical transformations similar 
to those I have obtained. 

By extending these researches, a large number of 
facts of the same order will certainly be discovered. 
Chemistry already possesses a certain number of 
them. There are, perhaps, as I have said, no 
bodies more dissimilar than white and red phos- 
phorus. In certain of their fundamental chemical 
properties, amongst them their capacity for oxidation, 
they differ from each other almost as much as 
sodium from iron. Yet it is sufficient to add to 

^ In Europe this experiment seems to have passed almost unnoticed. 
Dr. Parodi of Cairo says, however, that he has repeated it w^h 
perfect success, and, apparently, much to his own astonishment. 
(See Bulletin de Vlnstilut Egypt ien^ Sec. 4, No. 4 (9th Noveml^er 
1904) pp. 464 et seg.) — F. L. 


white phosphorus traces of iodine or of selenium to 
transform it into red phosphorus. 

The instances of iron and steel and of pure 
and ordinary iron are no less typical. It is known 
that steel, so dissimilar to iron in hardness and in 
appearance, only differs from it chemically by the 
presence of a few thousandth parts of carbon. It 
is also known that the properties of pure iron are 
absolutely different from those of ordinary iron. ^^^^ 

This last, in fact, does not oxidize in dry air. Pure mKf^ 

iron obtained by reducing sesqui-oxide of iron by ^^^ 
means of heated hydrogen is so oxidizable that it 
spontaneously ignites in air, whence the name of 
pyrophoric iron given to it. 

It might even be well, in the presence of such facts, 
to inquire whether the classic properties of several 
ordinary metals may not be solely due to some 
infinitesimal quantity of other bodies, the presence 
of which is often hidden from us, and which we call 
impurities when they are revealed to us by analysis. 
We shall see that the diastases, the most important 
compounds of organic chemistry, lose all their pro- 
perties when deprived of the traces of certain metals 
whose existence was formerly not even suspected. 

The facts put in evidence by my researches and by 
those of the same order which I have brought 
together seem therefore to prove that simple bodies 
have not the invariability attributed to them. To 
admit that they are not invariable is to say that it may 
become possible to transform them, and to come back 
to the old problem of the transmutation of sub- 
stances which so exercised the alchemists of the 
middle ages, and which modern science has finally 
judged to be as unworthy of its researches as the 


squaring of the circle or perpetual motion. Long 
considered as chimerical, it nowadays comes again 
to the front and occupies the" minds of the most 
eminent chemists.^ 

" The great modern discovery to be realized to-day," 
wrote M. Moissan, a few years back, "would not 
therefore be to increase by a single unit the number 
of our elements, but, on the contrary, to diminish 
it by passing in methodical fashion from one 
simple body to another. . . . Shall we finally attain 
that transformation of simple bodies into one 
another which would play in chemistry as important 
a part as the idea of combustion when grasped by 
the acute mind of Lavoisier ? . . . Great questions 
here stand for solution. And this mineral chemistry, 
which we thought to be exhausted, is yet only at its 
dawn." In reality, on the modern theory of electro- 
lytic dissociation, chemists are obliged to admit, as 
everyday occurrences, transmutations quite as sin- 
gular as those dreamed of by the alchemists, since 
it suffices to dissolve a salt in water to entirely 
transforni its atoms. 

It is known that, according to the theory even 
then old but greatly developed a few years ago by 
Arrhenius, in an aqueous solution of a salt — chloride 
of potassium, for.' example — the atoms of the chloride 
and of the potassium separate and remain present 
in the bpsom of the liquid. Chloride of potas- 
sium is dissociated by the sole fact of its solution 
into chlorine and potassium. But, as potassium 
is, a metal which cannot remain in water without 
violently decomposing it, nor find itself in pres- 

* ^Cf, Sir William RamFay's article in the Athemrtim of loth March. 
190^.— F. L. 


ence of chlorine without energetically combining 
with it, it must perforce be admitted that the 
chlorine and the potassiurh of this solution have 
acquired new properties bearing no analogy to their 
ordinary properties. It follows from this that their 
atoms have been entirely transformed. This is 
acknowledged, moreover, since the phenomenon is 
interpreted by the assertion that the differences noted 
are due to the fact that, in the solution, the atoms of 
chlorine and the atoms of potassium are formed of 
ions bearing electric charges of opposite signs, which 
would neutralize each other in ordinary chlorine and 
potassium. There must therefore exist two very 
different kinds of potassium, the potassium of the 
laboratory with all the properties we observe in it, 
and the ionized potassium without any relationship 
to the first; and the case is the same with chlorine. 
This theory has been accepted because it facilitates 
calculations, but it will be evident that it would 
lead us to consider the atom as the easiest thing in 
the world to transform, since it would suffice to 
dissolve a body in water in order to obtain a radical 
transformation of its characteristic elements. 

Several chemists, moreover, formerly went some 
length in this direction. H. Sainte-Claire Deville 
declared to his pupils that he did not believe in the 
persistence of elements in compounds. W. Ostwald, 
Professor of Chemistry at the University of Leipsic, 
likewise affirms that the elements cannot continue to 
subsist in chemical combinations. " It is," according 
to him, " contrary to all evidence to allow that matter 
in a chemical reaction does not disappear and make 
room for another matter endowed with different pro- 
perties." Oxide of iron, for instance, would nowise 


contain iron and oxygen. When oxygen is made to 
act on iron, a complete transformation is effected of 
the oxygen and the iron, and if, from the oxide thus 
formed, oxygen and iron are subsequently extracted, 
it is only by performing the converse transformation. 
" Is it not nonsense," writes M. Ostwald, " to claim 
that a definite substance can continue to exist with- 
out possessing any of its [original] properties ? In 
point of fact,. this purely formal hypothesis has only 
one object — that is, to make the general facts of 
chemistry agree with the utterly arbitrary notion 
of an unalterable matter." 

It certainly seems to result from what has been 
said above that the equilibria of the elements con- 
stituting the 4toms can be easily modified, but it is 
indisputable also that they have an invincible tend- 
ency to return to certain forms of equilibrium special 
to each ; since, after every possible modification, they 
are always able to return to their primary form of 
equilibrium. It may therefore be said that, in the 
present state of science, the variability of chemical 
species is proved, but that with the means at our 
disposal it is only realizable within certain limits. 

§ 2. Variability of Compound Bodies, 

What I have just said of the variability of simple 
bodies and of the means which allow it to be effected 
appHes equally to compound chemical bodies. There 
exists at the present day a very important industry — 
that of the manufacture of incandescent lamps — 
founded on nothing but the principle of the trans- 
formation of certain properties of compound bodies 
in the presence of slight quantities of other bodies. 
When the mantles of these lamps are soaked in pure 


oxide of thorium, they do not become luminous on 
heating, or only very slightly so; but if to the oxide 
of thorium one per cent, of oxide of cerium be 
added, this mixture gives to the mantle that brilliant 
luminosity we all know. With an increase or a 
diminution in the quantity of oxide of cerium added, 
the incandescence diminishes at once. This was a 
very unforeseen phenomenon, and is the reason why 
the creation of this mode of illumination required 
lengthy researches. 

But it is, perhaps, in the chemical phenomena 
which occur in the interior of living beings that 
this same principle can be more frequently verified. 
Divers diastases^ entirely lose their properties if they 
are stripped of the traces of mineral substances they 
contain, especially manganese. It is probable that 
bodies like arsenic, which is now extracted in infini- 
tesimal doses from rhany tissues, exercise an important 
influence unsuspected by the earlier chemistry. 

It is probably to the actions exercised by the 
presence of bodies in very small quantities that 
are due the differences observed in compounds 
formerly considered identical, which, however, would 
seem to vary with their origin. In former times 
well-defined radicals, such as sugar, chlorophyll, 
haemoglobin, nicotine, the volatile essences, etc., were 
considered as identical, no matter from what living 
being they came. But Armand Gautier has estab- 
lished that this is an error: "Though still apper- 
taining to the same chemical family, these radicals, 
when isolated and closely studied, are modified from 
one vegetable race to another by isomerization, sub- 

^ Substances which cause diastasis or separation. The saliva, which 
converts starch into sugar, is a familiar example. — F. L. 


stitution, and oxidation; they have become^ in short, other 
definite chemical species, ... It is the same with the 
animal kingdom. There is not one haemoglobin, but 
several haemoglobins, each proper to its own species." 

In noting these differences between bodies similar 
to each other, but of different origin, Armand 
Gautier does not give their causes. It is by analogy 
that I have supposed the said differences to be pro- 
duced by traces of various substances, and by varia- 
tions in their quantity. I have already pointed out 
that organic ferments lose their properties the moment 
they are deprived of the small proportion of metallic 
matter they always contain. Haemoglobin, which 
seems to act as a catalytic ferment, contains quantities 
of iron varying greatly with the animal species. 

This principle of the transformation of the pro- 
perties of a substance by the addition of a very small 
quantity of another body has thus plainly a general 
importance.^ Yet it is only the enunciation of 

^ The interest of these considerations has not escaped the attention 
of all chemists. I find a proof of this in a note of M. Duboin, 
Professor of Chemistry at the Faculty des Sciences^of Grenoble, pub- 
lished in the Revue Scientijique, 2nd January 1904, from which I 
extract the following passage : — 

** The perusal of the recent memoirs of Gustave Le Bon has led me to 
a new theory on the constitution of bodies presenting several allotropic 
states. . . . 

** I think that of the three known varieties of phosphorus — white, 
red, and violet — one only would be a simple substance, the other two 
l)cing combinations of the first, with some element of extremely low 
atomic weight . . . analogous to particles emanated from radio-active 
bodies. . . . 

** When oxygen slowly oxidizes white phosphorus, it may lake away 
this element and combine with it to form ozone, which would thus be & 
combination of oxygen with this unknown element. 

"This is, no doubt, a hypothesis; but, if verified by experiments, 
it would amount to an incursion into that world of chemistry without 
balance, of which you were the first to point out the extent." 


empirical observations, of which the secret causes 
still remain hidden. The particular combinations 
thus formed, to which we shall return in a subse- 
quent chapter, altogether escape the fundamental 
laws of chemistry. 

The various appHcations I have made of this 
principle have proved to me that it will be fruitful 
and of practical use, not only in chemistry and 
physiology, but also in therapeutics. I base this 
assertion on some studies which I undertook 
several years ago on the totally new properties 
caffeine assumes when associated under certain con- 
ditions with very small doses of theobromine (an 
alkaloid which, when isolated, only acts on the 
organism in very large doses). From experiments 
made with registering instruments on various 
patients, several of which have been repeated in one 
of the laboratories of the Sorbonne by Professor 
Charles Henry, theobromized caffeine would seem 
to be the most energetic muscular stimulant known. 
Observations made on a certain number of artists 
and writers have likewise proved its singular power 
on intellectual activity. 

Experiments on the variability of compound 
chemical species have evidently not the same im- 
portance as those relating to the variability of simple 
bodies, since chemistry has for a long time known 
how to modify compound bodies by various reactions. 
If I have detailed them, it is to show that the. prin- 
ciple of the method which permits the properties of 
simple bodies to be varied is applicable to many 
compound bodies, and to draw attention to its con- 
sequences in advance. In the early mineral chemistry, 
any compound bodies — nitrate of silver, for instance 


— were considered as sharply defined substances 
formed by the combination of certain elements in 
strictly constant proportion. They are proBably 
nothing of the kind. The law of definite proportions 
is no doubt only an approximate law like the law of 
Mariotte, and only owes its apparent correctness to 
the insufficiency of our methods of observation. 

In so far as the variability of simple bodies is 
concerned, it should be pointed out that a very 
serious reason, deduced from my researches, will no 
doubt always be opposed to the subjection of the 
atom to complete transformations of equilibrium. I 
have shown that it is a reservoir of colossal energy. 
It seems therefore probable that to transform it 
entirely would require quantities of energy far 
superior to those at our command. 

But experiment proves that, without being able to 
definitely destrpy the atomic equilibria, we are 
allowed to modify them. We know, also, that, by 
very simple means, we can provoke the dissociation 
of matter, and consequently liberate a part of its 
energy. If, therefore, it is found impossible to add 
enoi)gh energy to the atom to transform it, we 
may at least hope to deprive it of a part of its energy 
— that is to say, to cause it to go down a step which 
it cannot retrace in the scale of its successive states. 
The atom deprived of a certain amount of energy can 
no longer be in the same state as before it lost it. 
Then it is, no doubt, that a veritable transmutation 
would appear. 

Bringing together the facts above demonstrated 
we arrive at this conclusion. Matter, from which 
our experiments have banished immortality, has 
no longer the fixity attributed to it. It follows 


further that all the ideas still dominant on the 
invariability of chemical species seem sentenced to 
disappear. When we see how profound are the so- 
called allotropic transformations, the transformation 
of bodies in electrolytic solutions and the complete 
transformations of several metals in presence of 
small quantities of certain substances; when, too, 
we see the facility with which bodies dissociate 
and reduce themselves to the same elements, we are 
naturally led to the renunciation of classical ideas 
and to the formulation of the following principle : — 

Chemical species are not invariable, any more than are 
living species. 




§ I. The Chemical Equilibria of Mineral Substaftces. 

The various elements may, by combination, give 
birth to bodies of an increasing complexity, from 
the minerals composing our globe up to the com- 
pounds forming the tissues of living beings. 

For a long time chemistry has been studying these 
combinations. It might therefore be supposed that 
we are about to enter a very well-known field. A 
very short stay there will show that, on the contrary, 
it constitutes a world full of utterly unknown 

As the mineral world was the only one accessible 
to the early methods of chemistry, it was naturally 
its first object of study. This was comparatively 
easy, and for this reason chemistry seemed at first 
a simple and precise science. 

Mineral substances are, in fact, generally formed 
by combinations of a very small number of- elements 
— oxygen, hydrogen, sulphur, etc. These combina- 
tions possess a constant composition and represent 
molecular edifices of small complexity in structure. 
It is only when we reach the compounds elaborated 
within the tissues of living beings that the pheno- 
mena become difficult to interpret. The molecular 



edifices then possess an excessive complication and 
a very great instability necessitated by the rapid 
production of energy requisite for the maintenance 
of life. The elementary edifice of the mineral 
world, composed of only a few stones, has become 
a town. The structure of organic substances some- 
times reaches such a degree of complication that 
it very often escapes us altogether. 

But however simple mineral edifices may appear, 
we are far from discerning the nature of the equilibria 
capable of giving them birth. It is solely the 
effects produced by these equilibria which are 
accessible to us. It is impossible for us to know 
wherein an atom of sulphur differs from an atom 
of oxygen or from any other atom, and equally 
impossible to understand the cause of the different 
properties in the compounds formed by their 
combinations. All that can be said is, that the 
relative position of the atoms seems to determine 
the properties of bodies much more than the 
attributes supposed to be inherent in these atoms. 
There are hardly any properties of elements which 
one cannot manage to transform by modifying the 
•structure of the molecular edifices in which they are 
united. What properties of the rigid diamond are 
found in the gaseous carbonic acid resulting from the 
combination of the diamond with oxygen ? What 
properties of the suffocating chlorine, of the alterable 
sodium are met with in the sea salt formed by their 
association ? Cacodyl and arsenic are very poisonous 
bodies, potassium a very caustic one; while caco- 
dylate of potassium, which contains 42% of arsenic, is 
a body in no wise caustic and utterly inoffensive. 

The properties of the elements then are capable of 



being entirely transformed by changes in the position 
of the atoms which enter into their structure. In 
chemistry, as in architecture, the shape of the edifice, 
has a far greater importance than that of the materials 
which compose it. 

It is principally in isomeric bodies — that is, bodies 
possessing the same percentage of component parts 
though manifesting different properties^ — that is 
shown the importance of the structure of molecular 
edifices. In the isomeric bodies termed metameric^ 
there is not only the. same proportional composition, 
but often the same number of atoms per molecule. 
The identity appears complete, but the difference in 
properties show that it cannot be so. 

In bodies termed polymeric the percentage com- 
position likewise remains identical, but the molecular 
weight varies either by condensation or by the 
splitting in two of the molecules. Such at least is 
the explanation given. If we could create polymeric 
elements from the metals we know we should probably 
succeed in creating new bodies, just as, by poly- 
merizing acetylene by simply heating it, we transform 
i^ into benzene. By the simple fact that three 
molecules of acetylene C^ H^ unite with each other, 
they form an entirely different body — tri-acetylene 
or benzene 3 (C2 H2) = C^ H^. 

So long as chemistry had to handle only the very 
simple compounds of the mineral world — water, 
acids, mineral salts, etc., of which the composition 

^ Or the quality which enables certain simple and compound bodies 
to change their properties without changing their composition. Ozone, 
which though identical with oxygen in other respects, yet possesises 
perfectly different properties, is a good instance. — F. L.. 

^ The term used for those bodies whose isomerism comes from the 
association of compounds. — F. L. 


was well known — it succeeded, by methodically 
varying their composition, in transforming their pro- 
perties and in creating new bodies at will. 

Take, for instance, as a combination with very 
little complication, the case of marsh gas or formene 
[i.e. methane] which is composed of carbon and 
hydrogen (CH^). One can, by successively replacing 
an atom of hydrogen by an atom of chlorine, obtain 
very different products, such as monochlorinated 
formene or chloride of methyl (CH^ CI), bichlorinated 
formene (CH^, CP), and trichlorinated formene or 
chloroform (CH, Cl^). If the last atom of hydrogen 
be taken from the combination, it becomes per- 
chloride of carbon (CCl^). 

All these reactions, being very simple, can be 
expressed by very simple formulas. Had chemistry 
stopped at this phase, it might have been considered 
as a perfe9tly constituted science. The study of the 
chemical equilibria of organic substances has shown 
the insufficiency of the early notions. 

§ 2. The Chemical Equilibria of Organic Substances. 

As soon as chemistry passed the bounds of the 
mineral world and penetrated into the study of the 
organic world, its phenomena became more and more 
complex. It was quickly noted that there existed 
equilibria independent of the percentage composition 
of bodies, and that, consequently, the customary 
formulas could not express them without giving t^e 
same formulas to very dissimilar bodies. It was 
necessary, therefore, to discard the early methods, 
and have recourse to geometrical figures, in order to 
approximateily represent the structures coming to 


light. It was at first supposed — against all likeli- 
hood, however — that atoms ranged themselves on one 
plane according to geometrical lines, of which the 
hexagon was the type. Then it was at length under- 
stood that they were perforce disposed according to the 
three dimensions of space, and they then came to be 
represented by solid figures typified by the tetrahe- 
dron. Thus was born stereo-chemistry, which, without 
certainly telling us anything of the inaccessible archi- 
tecture of atoms, permitted certain known facts to 
be put together and others to be discovered. But 
these diagrammatic structures, without any relation- 
ship to reality, in the long run showed themselves very 
insufficient. We were then led to suppose that the 
elements of bodies were not in static but in dynamic 
equilibrium. From this came a new chemistry, still 
in course of formation, which might be called kine- 
matic chemistry. In its formulas atoms are represented 
by little circles, round which are drawn arrows indi- 
cating the supposed direction of their rotation. The 
idea that atoms and their component elements are in 
perpetual motion in bodies is quite in conformity 
with the notions I have set forth, but to interpret by 
diagrams such complicated movements is evidently 
beyond our powers. 

The most striking feature in the current conception 
is that chemical compounds appear more and more 
as mobile equilibria, varying with the external condi- 
tions, such as temperature and pressure, to which 
they are subjected. 

The reactions indicated by chemical equations owe 
their apparent rigidity only to the fact that the 
medium in which they are realized does not noticeably 
vary. When these conditions are much modified, 



the reactions immediately change and the usual 
equations are no longer applicable. What is called 
in chemistry the phase law was established through 
this fact being noticed. Any chemical combination 
ought always to be regarded as a state of equilibrium 
between the external forces which surround a body 
and the interior forces which it contains. 

So long as chemistry had only to study very simple 
mineral or organic compounds elementary laws 
were sufficient, but closer examination showed that 
substances existed to which none of the known laws 
of chemistry could be applied, and these substances 
•are just those which play a preponderating part in 
the phenomena of life. A living being is made up 
of an aggregate of chemical compounds formed by 
the combination of a small number of elements so 
associated as to compose molecular edifices of very 
great mobility. This mobility, necessary for the 
rapid production of a great quantity of energy, is one 
of the very conditions of existence. Life is bound up 
in the constant construction and destruction of very 
complicated and very unstable molecular edifices. 
Death, on the contrary, is characterized by the 
return to less complicated molecular edifices of very 
great stability of equilibrium. 

A great number of the chemical compounds of 
which the aggregate constitutes a living being, pos- 
sess a structure and properties to which none of the 
old laws of chemistry are applicable. In this struc- 
ture is found a whole series of bodies — diastases, 
toxins, anti-toxins, alexins, etc., of which the existence 
has only, in most cases, been revealed by physio-' 
logical characteristics. No formula can express their 
composition, and no theory explains their properties. 


On them depend the majority of the phenomena 
of life, and they possess the mysterious quality 
of producing very great, effects without any apparent 
change in their composition and simply by their 

It is thus that the protoplasm which is the funda- 
mental substance of the cells, never appears to 
change, although by its presence it determines the 
most complicated chemical reactions, notably those 
which result in the transformation of bodies contain- 
ing energy at low potential into bodies whose 
potential is higher. The plant is able to manufac- 
ture, with compounds of small complication, such as 
water and carbonic acid, very complicated oxidizable 
molecular edifices, which are charged with energy. 
From the energy at a low tension which, surrounds 
it, it consequently manufactures energy at a high 
tension. It compresses the spring which other 
beings will relax to utilize its force. 

The chemical edifices, which humble cells are able 
to form, comprise operations, not only the most skilful 
in our laboratories — namely, etherification, oxida- 
tion, reduction, polymerization, etc., but many more 
skilful still which we are unable to imitate. By 
means which we do not even suspect, the vital cells 
are able to construct those complicated and varied 
compounds — albuminoids, cellulose, fats, starch, etc., 
necessary for the support of life. They are able to 
decompose the most stable bodies, such as chloride 
of sodium, to extract the nitrogen from ammoniacal 
salts, the phosphorus from phosphates, etc. 

All these operations, so precise, so admirably 
adapted to one purpose, are directed by forces of 
which we have no conception, which act exactly as 


if they possessed a power of clairvoyance very 
superior to reason. What they accomplish every 
moment of our existence is far above what can be 
realized by the most advanced science. 

A living being is an aggregate of cellular lives. So 
long as we are unable to comprehend the phenomena 
which take place in the bosom of an isolated cell, 
and have not discovered the forces which direct 
them, it will be of no use to build philosophical 
systems to explain life. Chemistry has, at least, 
achieved this much progress that it puts us face to 
face with a world of totally unknown reactions. For 
the former certainties of a too young science, it has 
finally substituted the uncertainties with which a more 
advanced science is ever burthened. They should 
not, however, be made too prominent, for the length 
of the journey before us would paralyze all efforts. 
Happily, those who enter upon these studies do not 
see how little advanced they are, and very often their 
teachers do not see it either. There is no dearth of 
learned formulas to conceal our ignorance. 

What part may intra-atomic energy play in the 
reactions as yet so little known to us, which take 
place in the bosom of the cells ? This is the point 
into which we will now inquire. 



§ I. Intra-atomic Chemistry. 

I HAVE just briefly demonstrated the existence of 
chemical actions which reveal certain eq.uilibria of 
matter hitherto completely unknown. Without 
claiming to be able to determine the nature of these 
equilibria, will it not now be possible to more or less 
foreshadow their origin ? It seems extremely prob- 
able that a large number of the inexplicable reactions 
we have mentioned, instead of only affecting mole- 
cular edifices, affect atomic edifices also, and 
bring into play the important forces of which we 
have proved the existence within them. Ordinary 
chemistry can displace ,the materials of which com- 
pounds are formed, but has not hitherto thought of 
dealing with these materials which it has considered 
to be indestructible. 

Whatever interpretation may be given to the facts 
to follow, it is certain that they prove the existence 
of equilibria of matter which none of the early 
theories of chemistry could explain. We see in 
them important actions produced by reactions so 
slight that our balances cannot detect them, and 
phenomena which none of the doctrines of chemistry 

have foreseen, and which for the most part contradict 



them. We are on the threshold of a new science 
where our ordinary reagents and balances can be no 
help, since it is a question of reactions whose effects 
are enormous, notwithstanding that but infinitely 
small quantities of matter are brought into play. 

The fundamental phenomena which reveal the 
dissociation of matter having been referred to else- 
where, it would be useless to go into the subject 
anew. The facts I am about to enumerate prove, in 
my opinion, that this dissociation has an important 
bearing on many phenomena hitherto unexplained. 

These facts cannot be classed in anv methodical 
fashion, since we have to do with a science yet 
unborn. I shall therefore confine myself to de- 
scribing them in a series of paragraphs, without 
endeavouring to present them in the orderly manner 
which their fragmentary character does not allow. 

§ 2. Colloid Metals. 

One of the best types of substances which elude 
the ordinary laws of chemistry is represented by 
the colloid metals. One of the methods of pre- 
paring them should alone suffice to indicate, apart 
from their very special properties, that their atoms 
must be partly dissociated. We have seen that, 
from the metallic poles of a static machine in 
motion there issue, as the result of the dissociation 
of matter, electrons and ions. Instead of a static 
machine let us take for the convenience of the experi- 
ment, an induction coil, the poles of which terminate 
in rods of the metal we wish to dissociate — gold or 
platinum, for instance — which are plunged in distilled 
water. By making sparks pass between the two rods, 
as described by Bredig, a cloud will be seen to form 


round the electrodes. After a certain time, the 
liquid becomes coloured and contains, in addition to 
the metallic particles torn from the electrodes and 
separable by filtration, something unknown and 
proceeding from the dissociation of the metal. It 
ig to this unknown thing that the name of colloid 
metal has been given.^ If the operation be long 
continued the colloid ceases to form, as if the liquid 
were saturated. 

: The properties of metals in a colloidal state are 
absolutely different from those of the body from 
which they emanate. In the prodigiously small 
proportion of ^j^x^th of a milligramme per litre, the 
colloid metal exercises the very energetic action 
which we will demonstrate later on. 

The liquid in which the colloid metal is found is 
coloured, but it is impossible to separate anything 
from it by filtration, or to perceive in it with the 
microscope any particles in suspension, and this 
shows that these particles, if they exist, are inferior 
in size to the wave lengths of light. 

The ionic theory being applicable to most 
phenomena, it has naturally been applied to the 
colloids. A colloidal solution is to-day considered 
as containing granules bearing electric charges — 
some positive, the others negative. But whatever 
this rather too simple doctrine be worth, it is evident 
that a colloid metal has retained no traces of the 
same metal in the ordinary state. Its atoms have 
probably undergone a commencement of dissociation, 

* There are chemical methods of preparing metals, notably silver, 
in the state called colloidal, but it is nowise proved that these metals 
are identical with the bodies obtained by the electric spark, in the 
manner just described. 


and it is for this very reason that they no longer 
possess any of their former properties. Colloidal 
platinum or gold are certainly no longer either gold 
or platinum, though made from these metals. 

The properties of colloid metals have, in fact, no 
analogy with those of a salt of the same metal in 
solution. By certain of their actions they resemble 
far more some organic compounds, notably the oxy- 
dases, than mineral salts. They present the greatest 
analogies with the toxins and the ferments, whence 
the name of inorganic ferments sometimes applied 
to them. Colloidal platinum decomposes oxygenated 
water as do certain ferments of the blood ; it trans- 
forms alcohol bv oxidation into acetic acid in the 
same way as does the mycoderma aceti. Colloidal 
iridium decomposes formiate of lime into carbonate 
of lime, carbonic acid, and hydrogen after the 
manner of certain bacteria. More curious still, 
bodies, which like prussic acid, iodine, etc., poison 
organic ferments, paralyze or destroy in the same 
manner the action of colloid metals. 

The properties, at once so special and so energetic, 
of these metals led perforce to the study of their 
action on the organism, which is very intense. It is 
to their presence in various mineral waters that 
Professor Garrigou attributes several properties of 
these waters — that of abolishing the phenomena of 
intoxication, for example. M. Robin has employed 
colloid metals as a remedy for sundry affections, 
notably typhoid fever and pneumonia, by injecting 
from 5 to 10 cubic centimetres of a solution con- 
taining 10 milligrammes of metal per litre. The 
result was a considerable increase of the organic 
exchanges, and of the oxidation of the elimination 


products as revealed by an over-production of urea 
and uric acid. These solutions being, unfortunately, 
very rapidly alterable, their practical use is very 

There is, it will be seen, no relationship, close or 
distant, between the colloid metals and those from 
which they are derived. No chemical reaction 
can explain the proporties they possess. Their 
mode of preparation authorizes the supposition that 
they contain, as I have said, certain elements of dis- 
sociated matter. I have, however, not observed in 
them any phenomena of radio-activity, but it will be 
readily understood that if these phenomena arise 
during the dissociation of matter, there is no reason for 
their appearance when matter is already dissociated. 

Besides metals, many substances can exist in the 
state termed colloidal, and there is now a tendency 
to ascribe to this unknown form of the material 
equilibria a preponderant part in physiology. Proto- 
plasm, for instance, would thus be only a mixture 
of colloidal substances — a fact, however, which 
throws very little light on its marvellous properties. 

§ 3. The Diastases, the Enzymes, the Toxins, and 

Actions by Presence. 

To the colloid metals obtained by the dissocia- 
tion of various simple bodies must be compared the 
compounds classed under the name of diastases, 
toxins, enzymes, etc., whose reactions are near akin 
to those of the colloid metals. Their chemical 
constitution is utterly unknown. They act almost 
exclusively by their presence and are sometimes 
extremely poisonous in almost imponderable doses. 


According to Armand Gautier, two drops of the 
toxin of tetanus containing 99% of water, and 1% 
only of the active substance — which would hardly 
represent a milligramme — is sufficient to kill a 
horse.^ A gramme of this substance would suffice, 
he says, to kill 75,000 men. Such energies as these 
make one think of those which very slight atomic 
dissociations might manifest. 

At the time when bacteria were believed to con- 
stitute . the active agent of intoxications, it was 
jiossible to explain by their rapid multiplication 
the intensity observed in their effects, but it is now 
known that the toxins remain just as active after the 
bacteria have been separated by filtration. The 
living substance called yeast transforms glucose into 
alcohol and carbonic acid, but after having killed 
this yeast by heating it to a certain temperature, a 
substance can be extracted from it deprived of all 
organisms and called zymase, as capable of pro- 
ducing fermentation as the living yeast itself. The 
phenomena attributed a few years ago to micro- 
organisms are therefore due to non-living chemical 
substances fabricated by them. 

The part played by the various substances jUst 
mentioned in the phenomena of life is a very pre- 
ponderant one. Most often it is only physiological 
reactions which reveal their existence and allow 
them to be isolated. All we know of them is that 

^ Insignificant traces of various substances are sufficient to paralyze 
the action of the . diastases. There are poisons with poisons of 
their own. They resist certain energetic reagents and are influenced 
by traces of seemingly very inoflensive substances. Such violent 
products as prussic acid, corrosive sublimate and nitrate of silver have 
no effect on the venom of the cobra, while traces of an alkaline salt 
pxcYsnt it from acting. 


they lose their properties if deprived of the infinitely 
small quantities of mineral matters that they contain 
under a form that we suppose to border on the 
colloidal state. 

Most of the above bodies — colloid metals, dias- 
tases, ferments, etc. — possess the property, very 
inexplicable as yet — of acting, at least in appearance, 
by their presence alone. They do not appear in the 
products of the reactions which they excite. These 
actions of presence, also called catalytic , have been 
observed for a long time in chemistry. It was known, 
for example, that oxygen and sulphurous acid, though 
without action one on the other, unite to form 
sulphuric acid in presence of platinum black without 
this latter taking part in the reaction. So nitrate of 
ammonia, though ordinarily unalterable, also gives 
a continual disengagement of nitrogen in presence of 
platinum black. This latter body does not combine 
with oxygen, but it can absorb 800 times its own 
volume of it. It is supposed — but this is evidently 
only an hypothesis — that it generally acts by borrow- 
ing oxygen from the air and conveying it to the 
substances with which it is in contact. 

Among the substances of which one might strictly 
say that they act only by their presence is found the 
vapour of water, which, in extremely small doses, 
plays an important part in various reactions. Per- 
fectly dry acetylene is without action on hydride of 
potassium, but in presence of a trace of humidity the 
two bodies react one on the other with such violence 
that the mixture becomes incandescent. Well-dried 
carbonic acid is also without action on hydride of 
potassium, but in presence of a slight quantity of 
steam it produces a formiate. It is the same with 


many other bodies — ammoniacal gas and hydro- 
chloric gas, for example, which ordinarily combine 
with the emission of thick, white fumes, but no 
longer do so after having been carefully dried. It 
will be remembered that I noted that by adding to 
dried salts of quinine traces of water vapour they 
become phosphorescent and radio-active. 

Although catalytic actions were early known, it is 
only in the last few years that they have been proved 
to play a preponderant part in the chemistry of 
living beings. It is now admitted that the disastases 
and various ferments whose r6le is so important act 
only by their presence. 

On closely examining the r61e of bodies acting by 
their mere presence, we note that they behave as if 
energy were transported from the catalyzing body to 
that catalyzed. This fact can hardly be explained, 
in my idea, unless by the catalyzing body undergoing 
the commencement of atomic dissociation. We 
know that, by reason of the enormous velocity 
possessed by particles of matter during its dissocia- 
tion, considerable quantities of energy can be pro- 
duced by the dissociation of a quantity of matter so 
imponderable as to elude all attempts to weigh it. 
The catalyzing substances should therefore be simply 
liberators of energy. 

If this be really the case, we ought to be able to note 
that the catalyzing body at length undergoes a certain 
alteration. Now, this is exactly what is verified by 
observation. Platinum black and the colloid metals 
are in the long run worn out — that is to say, by use 
they lose a great part of their catalyzing action. . 


§ 4. Oscillating Chemical Equilibria. 

All the reactions above indicated are, I rejjeat, 
inexplicable by current id^as. They are even con- 
trary to the most important laws of chemistry, such 
as those of definite and of multiple proportions. We 
see, in fact, some bodies transform themselves under 
the influence of imponderable doses of certain sub- 
stances, while others excite intense reactions bv 
their mere presence, etc. 

The study of early chemistry left on the mind the 
notion of very stable products, of well-defined and 
constant composition, and incapable of modifica- 
tion except by violent means such as high tem- 
peratures. Later on arose the notion of compounds 
less fixed, capable of receiving a whole series of 
modifications connected with the variations of the 
medium or of the temperature and of the pressure 
to which they are subjected. Of late years the 
notion has gradually arisen that any body whatever 
simply represents a state of equilibrium between the 
internal elements of which it is formed and the ex- 
ternal elements acting upon it. If this connection is 
not plainly apparent in some bodies, it is because 
they are so constituted that their equilibria maintain 
themselves without perceptible changes within the 
limits of fairly large variations of the medium. 
Water can remain liquid in variations of temperature 
ranging from 0° to 100" C, and most metals do 
not appear to change their state within still wider 

It is now necessary to proceed farther and admit 
that outside the only factors till now regarded by 
chemistry — mass, pressure, and temperature — there 


are others in which occur the elements resulting 
from the dissociation of atoms. These elements 
should be capable of giving to bodies equilibria of 
such mobility that these equilibria could be de- 
stroyed or regenerated in a very short time under 
very slight external influences. 

This succession of changes would be accompanied 
by the liberation of a certain quantity of the intra- 
atomic energy contained in matter. The actions by 
mere presence which are of such importance in the 
phenomena of life, may perhaps find an explanation in 
this theory. It was my studies on phosphorescence 
which led me to this hypothesis. It will be recollected 
that pure substances, various sulphides, phosphates of 
lime, etc., are never phosphorescent normally, and 
only become so when brought to a red heat for a 
length of time with traces of other various bodies — 
such as bismuth, manganese, etc. I have shown, on 
the other hand, that this elevation of temperature 
always provokes a dissociation of matter. It is 
therefore permissible to suppose that the elements 
proceeding from this dissociation have an active 
part in the unknown compounds then formed, 
which gives to such bodies the capacity for phos- 

The combinations thus obtained have precisely the 
characteristic pointed out above as belonging to ex- 
treme mobility — that is to say, of destroying and 
regenerating themselves very rapidly. A ray of blue 
light falling on a screen of sulphide of zinc, illumi- 
nates it in the tenth of a second, and a ray of red light 
falling on the same screen, destroys the phosphor- 
escence in the same space of time- — that is to say, it 
brings the screen back to its primitive state. These 



two contrary operations, necessarily implying two 
converse reactions, may be indefinitely repeated. 

However this may be, the facts enumerated in 
this chapter show us that chemistry is on the thres- 
hold of entirely new phenomena, characterized very 
probably by intra-atomic reactions accompanied by a 
liberation of energy. By reason of the enormous 
quantity of intra-atomic energy contained in matter, 
a loss of substance too small to be detected by our 
balances may be accompanied by a very great libera- 
tion of energy. 

In endeavouring to bring the phenomenon of the 
dissociation of atoms into the explanation of unex- 
plained chemical reactions, I have evidently only 
framed an hypothesis whose justification is not yet 
strong enough. It has at least the advantage of 
explaining facts hitherto without interpretation. It 
is certain that a phenomenon so important and 
frequent as that of the dissociation of matter must 
play a predomina;it part in many reactions. Intra- 
atomic chemistry is a science of which we barely 
see only the dawn. In this new science the old 
material of chemists, their balances and their re- 
agents, will probably find their occup^ition gone. 






§ I. Genesis and Evolution of Atoms. 

Barely forty years ago it would have been impos- 
sible to write, on the subject I am now treating, a 
single line deduced from a scientific observation, and 
one might have thought that thick darkness would 
always envelop the history of the origin and develop- 
ment of atoms. How could they, moreover, be sup- 
posed to evolve ? Was it not universally admitted 
that they were indestructible ? Everything in the 
world changed and was ephemeral. Beings suc- 
ceeded beings by assuming always new forms; stars 
were finally extinguished; but the atom alone did 
not submit to the action of time, and seemed eternaL 
The doctrine of its immutability reigned for two 
thousand years, and nothing allowed us to sup- 
pose that it might one day be shaken. 

We have run through the experiments which have 
at last ruined this old belief. We now know that 
matter vanishes slowly, and consequently is not 
destined to last for ever. But if the atoms are like-- 
wise condemned to a relatively ephemeral existence, 
it is natural to suppose they were not always what 
they are at the present day, and that they must 
have evolved during the succession of the ages. 
Through what successive phases have they passed ? 



What forms have they step by step assumed? 
What were formerly the different substances we see 
around us — stone, lead, iron, in a word, all bodies ? 
Astronomy alone could give some answer to such 
questions. Able to penetrate by spectrum analysis 
into the structure of the stars of various ages which 
illumine our nights, it has revealed to us the trans- 
formations to which matter is subject when it com- 
mences to grow old. We know that spectrum 
analysis proves an incandescent body to have a 
spectrum reaching further towards the ultra-violet as 
its temperature rises. The same spectrum, moreover, 
has a maximum brilliancy which likewise moves 
towards the ultra-violet when the temperature of the 
luminous source rises, and towards the red when it 
diminishes. We know, on the other hand, that the 
spectral rays of a metal vary with its temperature. 
Watteville has even shown that if potassium be 
introduced into a flame, its spectrum changes 
according as the metal is in the more or less heated 
regions of this flame. The spectroscope gives us, 
then, the means of knowing from what elements the 
stars are composed, and how they vary with the 
temperature. In this manner it has been possible to 
follow their evolution. 

The nebulae which show only the spectra of 
permanent gases like hydrogen, or products derived 
from carbon, must constitute, according to several 
astronomers, the first phase of the evolution of 
celestial bodies. By condensing they must form 
new stages of matter which end in the formation of 
stars. These latter represent very varjang periods of 

The whitest stars> which are also the hottest, as is 


proved by the prolongation of their spectrum into 
the ultra-violet, are composed of only a very small 
number of chemical elements. Sirius and a Lyrae, 
♦ for instance, contain almost exclusively incandescent 
hydrogen. In the red and yellow stars, stars less 
heated, which are beginning to cool and are there- 
fore of greater age, other chemical elements appear. 
First, magnesium, calcium, silicium, etc. Certain 
bodies are observed only in the coldest stars. It is 
therefore with the lowering of the temperature that 
the elements of atoms undergo new phases of evolu- 
tion, the result of which is the formation of certain 
simple bodies. 

It is probable that the solid elements we observe 
— gold, silver, platinum, etc. — are bodies which have 
lost different quantities of their intra-atomic energy. 
Simple bodies in a gaseous state-rnitrogen, hydrogen, 
oxygen — are the least numerous on our globe. To 
pass into a solid state, which they can only do at an 
extremely low temperature, they must first lose a 
very great amount of energy. 

It seems very doubtful if heat is the sole cause of 
the sidereal evolution of the atoms. Other forces 
most probably have acted in it. We know that 
variations in pressure may, as Deslandres has 
shown, cause considerable variations in the rays 
of the spectrum; "under increasing pressures new 
series are seen to arise which only existed in germ 
at lower pressures." 

To sum up, the observation of the stars shows us 
the evolution of the atoms and the formation of the 
various simple bodies under the influence of this 

We are ignorant of the nature and the mode of 


action of the forces capable of condensing a part of 
the ether which fills the universe into atoms of gas, 
such as hydrogen or helium, and then of transform- 
ing this gas into substances such as sodium, lead, or 
gold. But the changes observed in the stars are a 
proof that forces capable of effecting such trans- 
formations exist, that they have acted in the past, 
and that they continue to act in the present. 

In the system of the world unfolded by Laplace, 
the sun and the planets were at first a great nebula, 
in the centre of which was formed a nucleus animated 
by a rotatory motion from which were successively 
detached rings which later on formed the earth and 
the other planets. Gaseous at first, these masses 
progressively cooled, and the space at first filled by 
the nebula was no longer occupied save by a small 
number of globes revolving on their own axes and 
round the sun. It is allowable to suppose that the 
atoms were not formed otherwise. We have seen 
that each of them may be considered as a little solar 
/ system comprising one or several central parts, round 

which revolve at immense speed thousands of 
particles. It is from the union of these miniature 
solar systems that matter is composed. 

Our nebula, like all those still shining by night, 
must perforce have come from something. In the 
present state of science there is only, as far as we 
can see, the ether which can have constituted this 
cosmic starting point ; and this is why all investiga- 
tions always bring us back to consider it as the 
fundamental element of the universe. Worlds are 
born there and return thither to die. 

We cannot say how the atom was constituted nor 
why it at length slowly vanishes; but at least we 



know that an evolution similar to this pursues its 
way without halt, since we observe worlds in every 
phase of evolution from the nebula to the cooled 
planet, starting from suns still incandescent like our 
own. The transformations of the inorganic world 
now appear as certain as those of organized beings. 
The atom, and consequently matter, do not escape 
that sovereign law which causes the beings which 
surround us and the innumerable stars with which 
the firmament is peopled, to be born, to grow, and 
to die. 

§ 2. The End of Matter. 

I have attempted in this work to determine the 
nature of the products of the dematerialization of 
matter, and to show that they constitute by their 
properties substances intermediate between matter 
and the ether. 

The ultimate term of the dematerialization of 
matter seems to be the ether in the bosom of which 
it is plunged. How does it return to it ? What 
forms of equilibrium does it assume to affect this 
return ? Here we are evidently on the extreme limit 
of the things our intelligence can comprehend, and 
are inevitably compelled to form hypotheses; but 
they will not be vain if it be possible to give them 
precise facts and analogies for a support. 

When studying the origin of electricity we saw 
that it might be regarded as one of the most general 
forms of the dematerialization of matter. We recog- 
nized, moreover, that the final products of the dis- 
sociation of the radio-active bodies were formed of 
atoms of electricity. These last should therefore 


represent one of the last phases of the existence of 
material substances. 

What is the fate of the atom of electricity after the 
dissociation of matter? Is it eternal while matter 
is not ? If it possesses any individuality, how long 
does it keep it ? And if it does not keep it, wh^it 
becomes of the atom ? ] 

That the electric atom should be destined to have 
no end is very unlikely. It is on the extreme limit 
of things. If the existence of those elements had 
continued to exist, since their formation, under the 
influence of the various causes which produce the 
slow dissociation of matter, they would finally have 
accumulated to the extent of forming a new universe, 
or, at least, a kind of nebula. It is therefore likely that 
they at length lose their individual existence. But 
in what way, then, do they disappear ? Are we to 
suppose that their destiny is that of those blocks of 
ice which float in the Polar regions, and which pre- 
serve an individual existence so long as the sole 
cause of destruction which can annihilate them — a 
rise in temperature — does not attack them ? So 
soon as they are overtaken by this cause of destruc- 
tion, they vanish into the ocean and disappear. 
Such, doubtless, is the final lot of the electric atom. 
Once it has radiated away all its energy, it vanishes 
into the ether and is no more. 

Experiment furnishes a certain support to this 
hypothesis. I demonstrated with regard to the 
elements of dissociated matter emitted by the 
machines in our laboratories, that electric atoms 
in motiop are always accompanied by vibrations 
of the ether. Such vibrations have received the 
n^mes of Hertzian waves, radiant heat, visible light, 


invisible ultra-violet light, etc., according to the 
effect on our senses or on our instruments; but we 
know that their nature is the same. They may be 
compared to the waves of the ocean, which differ 
only by their size. . 

These vibrations of the ether, ever the companions NC 
of the electric atoms, most likely represent the form 
under which these vanish by the radiation of all 
their energy. The electric particle with an in- 
dividuality of its own, of a defined and constant 
magnitude, would thus constitute the last stage 
but one of the disappearance of matter. The last 
of all would be represented by the vibrations of the 
ether, vibrations which possess no more durable 
individuality than do the waves formed in water 
when a stone is thrown into it, and which soon 

How can the electric atoms proceeding from the 
dematerialization of matter preserve their individu- 
ality and transform themselves into vibrations of the 
ether ? 

All modern research leads us to consider these 
particles as constituted by whirls, analogous to 
gyroscopes, formed in the bosom of ether and con- 
nected with it by their lines of force. The question, 
therefore, reduces itself to this: how can a vortex 
formed in a fluid disappear into this fluid by causing 
vibrations in it ? 

Stated in this form, the solution of the problem 
presents no serious difficulties. It can be easily 
seen, in fact, how a vortex generated at the expense 
of a liquid can, when its equilibrium is disturbed, 
vanish by radiating away the energy it contains under 
the form of vibrations of the medium in which it is 


plunged. In this way, for example, a waterspout 
formed by a whirl of liquid loses its individuality and 
disappears in the ocean. 

It is, no doubt, the same with the vibrations of the 
ether. They represent the last stage of the de- 
materialization of matter, the one preceding its final 
disappearance. After these ephemeral vibrations the 
ether returns to its repose, and matter has definitely 
disappeared. It has returned to the primitive ether 
from which hundreds of millions of ages and forces 
unknown to us can alone cause it to emerge, as 
it emerged in the far-oif ages when the first traces 
of our universe were outlined on the chaos. The 
beginning of things was, doubtless, nothing else 
than a re-beginning. Nothing leads to the belief 
that they had a real beginning, or that they can 
have an end. 

If the views set forth in this work be correct, 
matter must have successively passed through very 
different stages of existence. 

The first of these carries us back to the very origin 
of the worlds, and escapes all the data of experiment. 
It is the chaos epoch of ancient legends. What was 
to be one day the universe was then only constituted 
of shapeless clouds of ether. 

By becoming polarized and condensed under the 
influences of forces unknown to us, which acted 
through age piled upon age, this ether was finally 
organized in the form of atoms: and it is from the 
aggregation of these last that matter as it exists in 
our globe or as we can observe it in the stars at 
various stages of their evolution, is composed. 

During this period of progressive formation, the 
atoms have stored up the provision of energy they 


have to expend in various forms — heat, electricity, 
etc. — in the course of time. While thenceforth 
slowly losing the energy first stored up by them, 
they have undergone various evolutions and have 
consequently assumed varying aspects. Once they 
have radiated away all their store of energy in the 
form of luminous, calorific, or other vibrations, they 
return by the very fact of these consecutive radia- 
tions, to their dissociation — to the primitive ether 
whence they came. This last, therefore, represents 
the final nirvana to which all things return after a 
more or less ephemeral existence. 

The evolution of the worlds would therefore, in the 
last analysis, comprise two very different phases — one 
the condensation of energy into the atom, the other, 
the expending of this energy. 

These brief sketches on the beginning of our 
universe and on its end evidently constitute only 
faint gleams projected into the deep darkness which 
envelops our past and veils our future. They are 
doubtless very insufficient explanations, but science 
can as yet offer no others. It has not yet any 
glimpse of the time when it may discover the true 
first cause of things nor even arrive at the real 
causes of a single phenomenon. It must therefore 
leave to religions and to philosophies the care of 
imagining systems capable of satisfying our longing 
to know. All these systems represent the synthesis 
of our ignorance and of our hopes, and are con- 
sequently only pure illusions; but these creations 
of our dreams have always been more seductive 
than realities, for which reason man has never 
ceased to choose them as guides. 


§ 3. Conclusions. 

The experiments analyzed in this work have 
allowed us to follow the atom from its birth to its 
decline. We have seen that matter, hitherto con- 
sidered as indestructible, slowly vanishes through the 
dissociation of its component elements. This matter, 
formerly regarded as inert and as having only the 
power of giving back the energy which had been com- 
municated to it, has, on the contrary, shown itself to 
us as an immense reservoir of forces. And from these 
forces are derived the majority of known modes of 
energy; molecular attractions, solar heat, and elec- 
tricity in particular. 

We have seen that matter can be dissociated under 
the influence of manifold causes, and that the products 
of its successive dematerializations constitute sub- 
stances intermediate by their properties between 
matter and the ether. The result of this is that the 
ancient dichotomy between the world of the pon- 
derable and that of the imponderable, formerly so 
widely separate, must disappear. And the study of 
the successive phases of the existence of matter has 
led us to the conclusion that the final term of its 
evolution is the return into the ether. 

In thus endeavouring to catch a glimpse of the 
origins of matter, of its evolution and of its end, we 
have step by step arrived at the extreme limits of 
those semi-certitudes to which science can attain, 
and beyond w^hich there is nothing but the darkness 
of the unknown. 

My work is therefore finished. It represents the 
synthesis of laborious investigations carried on during 
many years. Starting with the attentive observation 


of the effects produced by light on a fragment of 
metal, I have been successively led by the con- 
catenation of phenomena to explore very different 
fields of physics and to sketch in outline a synthesis 
of the universe. 

Without doubt, experiment has always been my 
principal guide; but to interpret the results obtained 
and to discover others, I have had to set up more 
than one hypothesis. As soon as the obscure regions 
of science are entered, it is impossible to proceed 
otherwise. If you refuse to take hypothesis as a 
guide you must resign yourself to chance for 
your teacher. " The r6le of the hypothesis," says 
Poincar^, "is one which no mathematician can 
afford to ignore, any more than can an experi- 
mentalist.'' To make hypotheses, to verify them by 
experiments, then to attempt to connect, by the aid 
of generalizations, the facts discovered, represents the 
stages necessary for the building up of all our know- 

In no other way have the great edifices of science 
been constructed. Imposing as they are, they still 
contain a large number of unverified theories, and 
it is often the least verifiable which play the greatest 
part in the direction of the researches of every epoch. 

It is rightly said that science is the daughter of 
experiment, but it is very rare that experiment has 
not hypothesis for its guide. This last is the magic 
wand which evokes the known from the unknown, 
the real from the unreal, and gives a body to the 
most shadowy chimeras. From the heroic ages 
down to modern times, hypothesis has always been 
one of the mainsprings of the man's activity. It is 
by religious hypotheses that the most imposing 


civilizations have been founded, and it is with 
scientific hypotheses that the greatest modern dis- 
coveries have been accomplished. Modern science 
accepts them no less than did our forefathers — and 
their r61e is, in reality, much greater now than ever it 
was, and no science could progress without their aid. 

Hypotheses above all serve to found those sovereign 
dogmas which occupy, in science, as preponderant a 
part as in religions and philosophies. The learned 
just as much as the ignorant man, has need of faith 
to give direction to his researches and to guide his 
thoughts. He can create nothing if not animated 
by some faith, but must not remain too long un- 
moved in that faith. Dogmas become dangerous so 
soon as they commence to grow old. 

It matters little that hypotheses and the beliefs 
they generate be insufficient; it is enough that they are 
fruitful, and they become so as soon as they provoke 
.research. Strictly verifiable hypotheses do not exist. 
Neither do absolutely positive laws. The most im- 
portant of the principles on which all the sciences 
rely are only truths approximately true within 
certain limits, but which, outside those limits, lose 
all exactitude. 

Science lives on facts, but it has always been great 
generalizations which have given them birth. A 
fundamental theory cannot be modified without the 
direction of scientific researches at once changing. 
From the single fact that ideas on the constitution 
and invariability of atoms are in course of transforma- 
tion, the doctrines which once formed a basis for 
the foundations of physics, of chemistry, and of 
mechanics, together with the direction of research, 
will have to change likewise. This new orientation 


in investigation will necessarily bring with it an 
outburst of new and unexpected facts. 

No one could dream of studying the world of 
atoms at the still recent time when they were 
thought to be formed of simple, irreducible, inacces- 
sible, ?Lnd indestructible elements. To-day we know 
that science is able to attack these elements, and 
that each one of them is a small universe of an 
extraordinarily complicated structure, a repository of 
forces formerly unknown, the magnitude whereof 
exceeds enormously all those hitherto known. That 
which chemistry and physics believed they knew best 
was in reality what they knew least. 

It is in these atomic universes, whose nature was 
so long misunderstood, that must be sought the 
explanation of most of the mysteries which surround 
us. The atom, which is not eternal as the ancient 
creeds asserted, is far more powerful than if it were 
indestructible and therefore incapable of change. 
It is no longer a thing inert, the blind spoFt of all 
the forces of the universe. These forces, on the con- 
trary, are its own creation. It is the very soul of 
things. It stores up the energies which are the 
mainspring of the world and the beings which 
animate it. Notwithstanding its infinite minuteness, 
the atom perhaps contains all the secrets of the 
infinite greatness. 




All the theories set out in the preceding pages rest on 
a long series of experiments. The scientific or philo- 
sophical doctrine which has not experience for its basis 
is deprived of interest and constitutes only a literary 
dissertation without meaning. 

I can only give in the following pages a brief 
summary of the experiments published by me during 
the last ten years. The memoirs in which they are 
described take up about 400 columns of the Revue 
Scientifiquey and I could not dream of republishing them 
here. Some of them, such as those on phosphorescence, 
Hertzian waves, the infra-red, etc., I have had to omit 

In all that follows I have especially endeavoured to 
give very simple experiments, and consequently easy 
to repeat. Naturally, I do not recapitulate those 
which have already been described, when this could be 
done without going into too many technical details in 
the first part. 

Much of the apparatus and a great part of the 
methods described in the following pages have no 
longer more than an historical interest. Both the one 
and the other have been brought considerably nearer to 
perfection by the physicists who have entered upon the 
path I marked out. There is always use, however, in 
knowing the apparatus employed at the outset of new 
researches, and for this reason I have described without 
alteration the instruments and methods which I have 

321 21 




I HAVE explained in a former chapter the principles 
of the methods employed in studying the dissocia- 
tion of matter — that is to say, its dematerialization. 
Before describing" them in detail I will recall in a few 
lines what I have said. 

All the means employed for verifying the dissociation 
of a body^ whether radium or any sort of metal, are 
identical. The characteristic phenomenon to be studied 
is always the emission of particles animated by an 
immense speed, deviable by a magnetic field, and 
capable of rendering the air a conductor of electricity. 
It is this last feature alone which was used to isolate 

There are other accessory characteristics^ such as 
photographic, impressions and the production of phos- 
phorescence and of fluorescence by the particles emitted, 
but they are of secondary importance. Besides, 99% of 
the emission from radium and the radio-active bodies is 
composed of particles without effect on the photo- 
graphic plate, and there exist radio-active bodies, such 
as polonium, which only emit such radiations.^ 

The possibility of deviating these particles by a 

* But see Wigger [of Gottingen]'s researches \Jahrbuch der 
Radioaktivitat uitd Elekiront% XL], for the fact that polonium and 
kindred substances do emit negative electrons or j3 rays, though these last 
are so slow-moving as to have hitherto escaped detection. This agrees 
with the latest researches of Rutherford and J. J. Thomson. — F.L. 




magnetic field constitutes the most important pheno- 
menon next to the aptitude for rendering" the air a 
conductor of electricity. It has enabled the identity 
between the particles emitted by radio-active bodies 
and the cathode rays of Crookes' tube to be settled 
beyond dispute, and it is the degree of deviation of 
these particles by a magnetic field which has rendered 
the measurement of their speed possible. 

As the measurement of the magnetic deviation of 
radio-active particles requires very delicate and costly 
apparatus, it is impossible to include it among easily 
performed experiments. These last being the only 
ones I wish to give here, I shall confine myself to the 
fundamental property possessed by particles of dis- 
sociated matter of rendering the air a conductor of 





The Way to prove that the Air has been Rendered a 
Conductor of Electricity by Radio-active Bodies, — The 
classic process employed 
to prove that a body emits 
particles of dissociated 
atoms capable of render- 
ing the air a conductor of 
electricity is exceedingly 
simple. It requires, in 
fact, no other instrument 
than a graduated electro- ^^^- 36.-Classic method used to 
^. . ^ V measure the radio-activity of 

scope. The substance X, bodies. 

supposed to be capable of 

dissociation, is placed on a plate A (Fig. 36). Above it 
is arranged a plate of metal B connected with a charged 
electroscope C. If conducting particles — ions or elec- 
trons — are emitted by the body X, the air becomes a 
conductor between the two plates and the electroscope 
is discharged. The rate of fall of the leaves is pro- 


portionate to the intensity of the emission of the 
particles by the dissociation. Or, the same results 
can be obtained by placing the bodies to be studied in 
a metal capsule placed directly on the electroscope. 
This is the means I generally employ. 

It must not be thought that the electroscope con- 
stitutes a rough and ready mode of examination incap- 
able of yielding exact measurements. Rutherford, who 
has studied it at great length, shows, on the contrary, 
that it is a very exact instrument, far superior, for most 
experiments, to the quadrant electrometer, and when well 
constructed much more sensitive than the best galvano- 
meter. The capacity c of a system with gold-leaf 
4 cm. long is, according to him, about one electro- 
static unit. If we call v the fall of potential of the 
leaves in seconds /, the intensity of the current i through 

c V 
the gas is given by the formula /= -r- In this way a 

current of 2 x lo'^^ amperes can be measured, which 
cannot be done with any galvanometer. But, for 
ordinary experiments, such a degree of sensitiveness 
is absolutely useless, and in the majority of cases it 
suffices to use an electroscope surmounted by a plate 
above or on which, as the case may be, the matter to 
be experimented on is placed. It is only necessary, 
though this point is indispensable, that the dielectric 
through which the rod supporting the gold leaves 
passes should be a perfect insulator. 

This last and very essential condition is, unfortu- 
nately, not realizable in any of the electroscopes 
manufactured in Paris. Only those of which the 
insulator is made with pure sulphur are really service- 
able,' and they are not found in commerce. One must 
therefore make the instrument oneself. Supports made 

1 Amber, which has a high dielectric strength, and is less fragile than 
sulphur, is now generally employed in England. — F. L. 



of paraffin, or of a mixture of sulphur and paraffin, do 
not long remain insulated, and the gold-leaf loses its 
charge. If forced to make use of them, the insulator 
must be cleaned, 
at least once a 
day, with a sheet 
of emery paper, 
an operation all 
the more neces- 
sary from the fact 
that the surface 
of the dielectric 
Id time becomes 
charged with elec- 
tricity. An elec- 
troscope can only 
be used for this 
kind of research 
when it does not 
give a loss greater 
than one angular 
degree in an hour 
after being cover- 
ed with its cap. 

Instead of the 
two classic gold 
leaves, it is better 
to use only one 
with a rigid cen- 
tral strip of oxi- 
dized copper. The 
angular deflection 
of the gold-leaf is then very sensibly proportionate to 
the potential. With the electroscope 1 use, a deflec- 
tion of the gotd-Ieaf of 90° corresponds to a charge 
of 1,300 volts, or about 14 volts per angular degree. By 

Fig. 37. —Apparatus for reducing the rapidity 
of the lass trf electricity prodaad by radio- 
aciivt bodies, — The radio-active sutstance is 
placed in a metal capsule placed on the 
plale of Ihe electroscope, and ihe speed of 
the discharge is varied by meaos a\ a 
metallic blade pl.iced at greater nr lesser 
dislancc from the plate. 


various contrivances, which need not be described 
here, electroscopes can be constructed so sensitive that 
I* will represent one-tenth of a volt. 

To read the fall of the gold leaves, the classic process 
of a microscope with a micrometer attached is not very 
convenient, especially in the case of rapid falls like 
those produced by light. It is much preferable to fix 
against one of the panes of glass forming the sides of 
the instrument a horn protractor, divided into degrees- 
and backed with a sheet of rough white paper. To 
read the divisions, place a small lamp in the dark 
a few yards from the instrument. The gold-leaf 
throws the shadow of its extremity on the unglazed 
paper, and thus may be read to the quarter of a 

To reduce the sometimes troublesome sensitiveness 
of the electroscope during experiments with radio-active 
bodies, it is only necessary to place a strip of metal 
at varying distances from the plate (Fig. 37). It acts 
not only by its capacity but also by reducing the 
quantity of air on which the ions act. A radio-active 
substance which, for instance, produces 18 degrees of dis- 
charge per minute only gives 12 if the strip be at 5 cm. 
distant from the plate, and 8 if brought 2 cm. nearer. 

Condensing Differential Electroscope, — For certain 
delicate experiments it becomes necessary to use an 
apparatus I have invented and called a condensing 
differential electroscope, which may be thus described: 
Having noticed from various experiments that the 
effluves proceeding from dissociated matter travelled 
round obstacles, I was led to invent an apparatus to 
make this impossible. By its use I discovered that all 
bodies contain, as do radio-active substances, an 
** emanation" which is constantly re-formed. In 
ordinary bodies it is only rapidly dissipated under the 


influence of heat, and takes several days to re-form, as 
will be seen later in these researches. 

A (Fig. 38) represents the ball of an electroscope 
mounted on a metallic rod, to the lower part of which 

Fig. 38. — Cottdensing differential electroscope of the author, 

are attached the gold leaves. This rod is supported by 
an insulating sulphur cylinder D. On this cylinder is 
placed an aluminium cylinder B, closed at the top. A 
second cylinder C, likewise of aluminium^ covers the 
first. It forms a Faraday's cage, and is only put in 


place after the electroscope has been charged.. This 
cage is the only part of the system which must not be 
insulated, and this is prevented by connecting it with 
the earth by the chain F. Moreover, it is placed on the 
metallic part of the electroscope, a condition which, of 
itself, would prevent its electric insulation. 

One must make these aluminium cylinders one*s-self, 
which is very easy. After procuring the thin sheet 
aluminium of commerce, it is cut to the height and 
width required and wrapped round a wooden cylinder, and 
the two ends fastened together by a paper band coated 
with glue. The top of the cylinder is closed by a thin 
plate of tin, which is folded over and glued round it. 

It will be seen that the cylinder C constitutes a 
Faraday's cage — that is to say, a screen completely 
protected against all external electrical influence. The 
leaves being charged and the large cylinder put in 
place, it is impossible to discharge the electroscope, 
even if a shower of sparks are made to fall on C. 

The method of charging the instrument is as follows : 
— ^Taking away the outer cylinder C and leaving the 
small cylinder B round the ball, the instrument is 
inductively charged by bringing a glass rod rubbed 
with silk to the cylinder B, which is then touched with 
the finger. It will be readily understood that in these 
conditions the cylinder B is charged negatively, the ball 
A positively, and the gold leaves negatively. The outer 
cylinder C is then put in its place and connected with 
the earth by a chain, an excess of precaution which is 
by no means indispensable. The whole system is then 
exposed to the influence one wishes to act on it. If the 
cylinder C be penetrated, the gold leaves draw together 
more or less rapidly. 

One can, if one pleases, make the electroscope receive 
a charge under these last conditions. Thus: — 

The instrument being charged as before, open the 


case of the electroscope and touch with a metal point 
the rod E bearing the gold leaves. They immediately 
fall. When the apparatus is immediately exposed to 
a radio-active influence — solar light, for instance — the 
leaves then separate several degrees. 

The mechanism of this charge is easy to under- 
stand. Let us suppose that the instrument has been 
charged by means of an ebonite rod rubbed with 
catskin. Naturally, it is not the light which pro- 
duces the electricity capable of charging the instrument. 
Its action is indirect. By touching the gold leaves, 
they were deprived of their positive charges, and there- 
fore fell; but the negative charge of the ball, which 
is maintained by the positive electricity of the small 
cylinder, could not be annulled. When this small 
cylinder begins to discharge, under the influence of 
the efiluves passing through the large cylinder, it will 
no longer be able to maintain the same quantity of 
negative electricity on the ball. Part of the electricity 
contained in the latter will then flow into the leaves, 
which, on being charged with electricity of the same 
sign, will diverge. The more the small cylinder dis- 
charges, the more the leaves will separate. The ball 
and the cylinder form, in a way, the two pans of a very 
sensitive balance. The separation of the gold leaves 
registers the slightest difference in the weights of the two 
pans. It is by reason of this analogy that I have given 
it the name of condensing diflerential electroscope. 

Such are, in a general way, the instruments used in 
my researches.^ I shall use many others, but they will 
be described in the chapters devoted to the various 

* I have myself found that the electroscope invented by Professor 
Kolbe, of St, Petersburg, when furnished with the extra caps here 
described, will answer all practical purposes. A more accurate instru- 
ment is described in the paper of Sir William Ramsay and Dr. Spencer 
presently referred to. — F.L. 



The bodies under study are arranged in strips, at an 
inclination of forty-five degrees above the plate of a 
charged electroscope (Figs. 39 and 45), but without 
any direct connection with it. When these bodies are 
struck by solar light, they emit effluves which discharge 
the electroscope if this last is charged positively. But 
these effluves have hardly any action if the electroscope 
be negatively charged. 

For demonstration purposes it is only necessary to 
use a simple strip of aluminium or zinc, first rubbed 
with emery paper, and fixed in any way above the 
positively charged plate of the electroscope. 

For quantitative experiments I employed the appara- 
tus represented in Fig. 39, but it is well to avoid as 
much as possible the use of the heliostat and to throw 
the light directly on to the metal to be experimented on. 
With a heliostat, the charge is sensibly reduced in 
consequence of the absorption of the ultra-violet by the 
surface of the mirror. The glass, indeed, hardly re- 
fracts more than 5 % of the ultra-violet rays. As to 
metals, their refracting power, very great in the infra- 
red, diminishes considerably with the length of the 
waves. Polished silver, for instance, hardly refracts 
10 to 15% of the incident ultra-violet radiations of the 
solar spectrum. At the beginning of the ultra-violet 
(0.400/A), on the contrary, it refracts nearly 80% of the 



Fig. 39. — Apparatus ttsid te demonstrate the dissociaiien of mailer by - 
the action of solar ligkt.— On (he left isi metal plale placed above 
3 positively charged electroscope unconnecte<l with it. In (he 
centce of the ligure is a support on which are placed the screens 
required to eliminate various parts of the spectrum. On the right 
is a helioslat for throwing the rays of the sun on to the metal plate. 
Its use must be avoided as much as passible, on account of the 
great absorption cf ultra.violet rays by (he surface of the minor. 


The electroscope may be charged by a dry battery 
or inductively by an ebonite rod rubbed with catskin. 
Care must be taken that the gold leaves are always 
brought to the same potential, and consequently 
separated by the same number of degrees from the 
vertical (20° in my experiments). The shadow of the 
leaves is thrown on to a plate of roughened glass 
divided into degrees, as seen in our figures. The in- 
strument is lighted by a lamp placed four or five metres 
off in a dark place at the end of the room where the 
experiments are made. 

The sources of light employed were: ist, the sun for 
the radiations of which the spectrum extends to 0.295/i; 
2nd, for the radiations extending further into the ultra- 
violet, I took, as source of light, the sparks of a 
condenser discharging between aluminium rods placed 
in a box closed by a plate of quartz covered with metal 
gauze, itself framed in a sheet of metal connected with 
the earth so as to be shut off from all electric influence. 
(Fig. 40. J 

In order that the experiments may be compared, the 
bodies to be acted on by light are all cut into strips 
10 cm. square, and placed at a distance of 15 centi- 
metres from the electroscope. The ball of this latter is 
replaced by a large copper plate, which is indispensable 
for obtaining a rapid discharge. Copper is a metal but 
slightly sensitive to solar light but very sensitive to the 
plectric light. It is, therefore, not necessary — though I 
did so — to shield this last from the action of light when 
operating in the sun; it is, on the contrary, indis- 
pensable to shield it from the luminous source when 
using the electric light. This is managed by the very 
simple arrangement shown in Fig. 40. 

To separate the various regions of the spectrum and 
determine the action of each, we interpose between the 
light and the body it strikes several screens (quartz 


trough containing a transparent solution of sulphate of 
quinine, g'lass 3"" thick, glass o. i™™ thick, mica o.oi"™ 

thick, rock salt, quartz, etc.). The transparency of 
these screens to the various rays is iirst determined by 
placing them before a spectrograph and noting, by 


means of the spectral rays photographed, the wave- 
length of the radiations which each transparent body 
allows to pass. The spectra here represented (Figs. 
41 and 42) show the results of some of these photo- 
graphs. Coloured glass, green and red excepted, 
cannot be utilized, for they really keep back very little, 
and only serve to reduce the intensity of the effect. 

Speaking of absorption, I would remark that absorbent 
bodies seem divisible into two classes — namely, specific 
absorbents and absorbents of intensity. By the first 
the spectrum is stopped dead in a particular region, 
whatever the exposure. The second sort, while being 
specific absorbents for certain regions, only act within 
a tolerably wide limit by reducing the intensity; the 
absorption in this case depends on the length of the 
exposure. Solutions of bi-chromate of potassium or of 
sulphate of quinine are specific absorbents; they only 
allow a particular region of the spectrum to pass, and 
this region is not prolonged whatever be the exposure. 
Uncoloured glass exercises, indeed, a specific absorption 
for certain regions, but throughout one relatively 
extended part it specially acts by reducing the intensity 
of the active rays — that is to say, by partially absorbing 
them. This is why the impression is not clearly stopped 
at a fixed point. Specific absorbents are limited in 
number, while absorbents of intensity are innumerable. 
All coloured glasses (red and dark green excepted) only 
reduce intensity. The evident proof of this is obtained 
by photographing the solar spectrum through coloured 
glass. By slightly lengthening the exposure through 
blue, yellow, violet, and other glasses, the totality of 
the visible solar spectrum is obtained. This point is 
interesting to physiologists, for it shows that the various 
experiments made on animals and plants with solar 
light filtered through coloured glasses prove absolutely 
nothing. The differences observed are due to causes 


Fig. 41. Fir,. 42. 

DitermincUion, hy means of phehgrapky, cf the transparency of todies 
for the various regions of the spectrum. — The first spectium on Ihe 
righl of Fig, 47 represents the spectium of the invisible uUra-violet 
of sparks from icOD without the interposition of any body. The 
three other spectra on the left of Fig. 42 represent the atsorplioD 
produced by uncoloured glass o.8»"n thick. The two spectra 00 
the right of Fig. 41 repiesenl Ihe continuation of the ultia-violet 
spectrum of iion without any screens. The fwo spectra on the 
left of Fig. 41 represent the absorption produced by a sliip of un- 
coloured glass'™ thick. This strip, of the thickness of ■ 
sheet of paper, is entirely opaque for a fairly extended region of 
the ipeclrum. The figures represent the graduation of Itie spectra 
in wave length. The spectrum of Fig. 42 goes from X — 0.400/1 to 
X=o.2S6f(. The spectrum of Fig. 41 represents the continuation 
of the ultra-violet region. It is graduated from ^ — 0.26^1, lo 
X = 0.33Ofi4 The solar spectrum extends, as we know, not twarly 
so far, ai it does not exceed X=o.295/b 



quite different from those hitherto invoked to explain 

The following is a table of transparency of the different 
screens or liquids employed by me to isolate the various 
regions of the spectrum. . In the region of the extreme 
ultra-violet of the spectrum I availed myself of the 
kindness of my learned friend M. Deslandres for the 
graduation of the wave-lengths. 

Table of the Transparency of Various Screens, 


I an. oj distilled water , 

Aqueous solution (/o%) of 
sulphate of quinine aci- 
dulated with sulphuric 

Esculine dissolved in al- 

Amfnoniacal sulphate of 

Aqueous solution {fO%) of 
bichromate of potas- 

Uranium glass half centi- 
metre thick 

Dark green glass . . . 


All the visible spectrum and the 
greater part of the ultra-violet. 

The visible spectrum up to about h. 
Keeps back all the ultra-violet. 

All the visible spectrum save a 
small part of the violet between 
h and H. Keeps back all the 

The visible spectrum from b and 
the ultra-violet up to N. 

Absorbs all the ultra-violet and the 
visible spectrum up to between E 
and D — that is to say, a little 
beyond the limits of the green. 

All the visible spectrum and the 
ultra-violet up to N. 

Only the part of the visible spectrum 
comprised between E and G. 



Transparency of Various Screens — continued. 



Ruby red glass .... 

All the infra-red from about X = 2At 
and the red part of the visible 
spectrum. Stops all the rest of 
the spectrum. 

Common window - glass 

j.jnim thick .... 

All the visible spectrum and the 
ultra-violet up to N and even up 
to if the exposure and the 
weather b^ suitable. 

Unco loured glass o.S**'*'' 

The whole of the visible spectrum, 
and the ultra-violet up to about 


Thin glass o.i*"**^ thick 
{jnicroscopic plate) . . 

All the visible spectrum and the 
ultra-violet up to about X= 0*25 2/*. 
Completely opaque to the next 




Action of the Various Parts of the Spectrum on the 
Dissociation of Matter, — By the method described above 
— i.e,^ by various screens whose transparency has been 
determined by the spectrograph,, it has been found 
possible to determine, by the rapidity of the electro- 
scope's discharge, the proportion of effluves emitted by 
each body during dissociation, according to the regions 
of the spectrum to which it is subjected; or, in other 
words, the intensity of the dissociation. From this it 
is seen that bodies are very unequally dissociate4 by 
light, and that the action exercised by the various 
regions of the spectrum differs greatly. These are the 
results obtained: — 

I St. Bodies sensitive to the radiations comprised in the 
solar spectrum — that is, not exceeding 0.295/x. — The 
majority of bodies are sensitive, but in extremely 
different proportions. The action may vary, in fact, 
from 20" of discharge of the electroscope in 5 seconds 
down to only 1° per minute. Some bodies are therefore 
about 500 times less sensitive than others. 

The following is the order of sensitiveness of the bodies 
most sensitive to sunlight: — Amalgamated tin, amalga- 
mated copper, aluminium recently cleaned, amalgamated 
silver, clean magnesium, clean zinc, amalgamated Iqad, 
mercury containing traces of tin. 

The least sensitive bodies — that is to say, those 



giving only from i" to 2* of discharge in 2 minutes, 
are the following: — Gold, silver, platinum, copper, 
cobalt, pure mercury, tin, cardboard, wood, phos- 
phorescent sulphides, and organic substances. With 
bodies of feeble dissociation, such as those just men- 
tioned, there is generally no effect observable except 
when the solar rays contain the region of the spectrum 
from M to U, a region which often disappears, even 
when the weather is very bright, as I will explain shortly. 
If, by means of the screens mentioned above and of 
their action on the electroscope, we ascertain the energy 
of the various regions of the solar spectrum on very 
sensitive bodies, such as amalgamated tm or aluminium, 
we shall find, representing by 100 the totality of the 
action produced, the following^ figures: — 

Action of the region of the solar 

spectrum reaching to X = o.400/-t - 6% 

Action of the region from - X = o.4C)0/-t to X = o.36o)u, - 9% 

Action of the region from - X = o.36o/-t to X = o.295At -85% 

It is possible, by various devices, to render certain 
bodies sensitive for regions where they otherwise 
are not so. Mercury and tin, separately, are bodies 
with little sensitiveness. It suffices, however, to add to 
the mercury utVtt of its weight in tin, to render it very 
sensitive for the region of ultra-violet comprised between 
A. = o.36o/x and A. = o.296/x. Mercury thus prepared is 
an excellent reagent for the study of the ultra-violet 
according to the hour, the day, and the season. If the 
added quantity of tin amounts to 10%, the mercury 
becomes sensitive for nearly the whole remainder of the 

2nd. Bodies which become very sensitive only to radia- 
tions having wave lengths less than 0.295/x. — Among 
these bodies I especially mention the following: — 
Cadmium, tin, silver, and lead. 


3rd. Bodies which are very sensitive only to radiations 
having wave lengths less than A = 0.252)14. — These are the 
most numerous. Among them may be mentioned the 
following: — Gold, platinum, copper, iron, nickel, organic 
substances, and various chemical compounds (sulphates 
and phosphates of soda, chloride of sodium, chloride of 
ammonium, etc.). After the metals, the most active 
bodies are lamp-black (20 degrees of discharge per 
minute) and black paper. The least active are living 
organic bodies — especially leaves and plants. 

The various chemical compounds dissociate like 
simple bodies, under the influence of light, but in rather 
different proportions. Phosphate of soda and sulphate 
of soda give 14" per minute, chloride of ammonium 8*, 
chloride of sodium 4**, etc. To verify the discharge, the 
bodies are made into a saturated solution. The solution 
is poured on a glass plate and made to evaporate. The 
glass plate is afterwards placed in the ordinary manner 
over the electroscope. 

The variations of discharge which I have given are 
only of value for the particular regions of the spectrum 
which have been enumerated. In proportion as regions 
of higher refraction are employed, the sensitiveness of 
the various bodies differs less, and tends toward 
equality, without, however, reaching that point. In 
the solar ultra-violet, gold, for instance, is almost 
inactive — about 500 times less active than aluminium. 
In the extreme ultra-violet of the electric light (starting 
from 0.252/x) it has, on the contrary, nearly the same 
rapidity of dissociation as this last metal. In this 
region of the ultra-violet, the difference of action 
between the least sensitive bodies (steel, platinum, 
and silver) and the most sensitive (amalgamated tin, 
for example) hardly varies more than from one to two. 

Moderate conductors — lamp-black, chemical com- 
pounds, wood, etc. — have in this advanced region 


of the spectrum a sensitiveness lower than that of 
metals. The discharge produced by the effluves of lamp- 
black, for instance, is much less than that of tin. 

Influence of Cleaning. — The action of cleaning is 
of the highest importance for metals subjected to the 
radiations contained in the solar spectrum. They 
should be vigorously cleaned every ten minutes with 
very fine emery-cloth, under penalty of seeing the dis- 
charge become 200 times less rapid. In the ultra- 
violet, starting from 0.252/x, the influence of the 
cleaning is still manifest, but much less so than in 
solar light. It will do if the surface has not remained 
uncleaned for more than about 10 days. After 10 days 
the discharge is hardly more than half what it is after 
recent cleaning. 

Influence of the Nature of the Electrodes. — When, in 
order to obtain radiations extending much farther into 
the ultra-violet than those of the solar spectrum, sparks 
from condensers (two Leyden jars placed in series on 
the secondary of an induction coil) are used, the inten- 
sity of the dissociation varies greatly with the nature of 
the metal of the electrodes. 

Aluminium points give a light, producing a dissocia- 
tion which, all things being equal, is nearly three times 
greater than that from gold points. Electrodes of 
copper and of silver give about the same figures as gold 

The first explanation which occurs to the mind is, 
that certain metals possess a more extended spectrum 
than others. But this explanation is nullified by recent 
measurements made by Eder,^ who has shown that the 

' Eder and Valenta, Normal Spectrum einiger EUmente {Kaiserlichen 
Academic der Wissenschafien, Vienna, 1899). 


spectra of most metals extend to about the same dis- 
tance into the ultra-violet. It is thus, for instance, 
that the spectrum of the sparks from gold, electrodes 
of which are the least active, extends quite as far 
(A = o. 185/x) as the spectrum from aluminium, electrodes 
of which are the most so. 

Nor does it seem that the differences of effect 
observed under the influence of the light produced by 
the sparks from various metals are due to differences of 
intensity of light. I find the proof of this in the fact 
that photographic paper prepared with chloride of 
silver, when placed for 60 seconds before the quartz 
window which closes the spark-box, presents the same 
intensity of impression with all metals excepting steei 
electrodes, when it is more intense than with the 
sparks produced by aluminium, this being precisely 
the opposite to what occurs in the power of the dis- 
sociating action of their light. During these short 
exposures it is only radiations below 0.310/* which act 
on the paper, as is proved by the fact that the inter- 
position of thin glass selected so as to stop the radia- 
tions of a wave length under A. = o.3io/x, also stops the 

The preceding facts relative to the very great differ- 
ence in electrodes according to the metals of which 
they are composed, would seem to prove that the 
spectrum of the various metals contains, in addition to 
light, a something with which we are not acquainted. 

Influence of the Varying Composition of the Solar Light 
on its Fitness to produce the Dissociation of Bodies, Dis- 
appearance at Certain Moments of the Ultra-violet, — 
When working with solar light it is very soon noticed 
that numerous factors may vary enormously the pro- 
duction of the effluves resulting from the dissocia- 
tion of matter, and consequently the intensity of the 


discharge. I shall come back to Ihis subject when 
treating of the so-called negative leak. 

As soon as I had organized a series of regular 
observations, consisting of experiments with bodies 
having a constant action, I perceived that, when work- 
ing for several days running at the same hour and in 
apparently identical weather, 1 suddenly observed con< 
siderable differences in the action of the electroscope. 

FlC. 43. — Pholographs showing Ike dhappearante of the solar ultra- 
violet en certain days caused iy iiaiiiewn injliieitces. — The upper 
band represents on ordinary solar spectrum exiending to Ihe 
border! of Ihe N tuy. The band beneath it shows [he disap- 
pearance of the solar ultia-vtolet starting from [he L lay, nolwith- 
standing the prolongation of the exposure. The lower band 
represents the Loial disappearance of Ihe ultra-violet when the 
specttum is phott^Taphed through a Iranspareni solution of sul- 
phate nf quinine. 

After having successively eliminated all intervening 
factors, I was left face to face with only one — the 
variation in the composition of the solar light. This 
was then only an hypothesis and had to be verified. 
As the variations were probably connected with the 
invisible parts of the spectrum, one single method of 
verification was at my disposal — the photography of this 
invisible region by the spectroscope. The only hint 


given in the text-books was that the ultra-violet dis- 
appears as the sun approaches the horizon, which, how- 
ever, the action of the electroscope ought to have 
sufiicijently indicated. But as I was noticing variations 
in the effects at the same hours every day and at a 
time when the sun was very high, this hint explained 

Photographs of the spectrum repeated for several 
months showed me, in conformity with my previsions, 
that from one day to another, and often on the same 
day, without apparently any cause for the phenomenon, 
the greater part of the solar ultra-violet, starting from 
the L or M rays, sometimes disappeared abruptly 
(Fig. 43). This phenomenon always coincided with the 
slowness of the discharge of the electroscope. The 
apparent state of the sky had no connection with this 
disappearance of the ultra-violet, for it was sometimes 
manifest in very bright weather, while, on the contrary, 
I noticed the ultra-violet remained constant under a 
very cloudy sky. However, here are some of the 
results obtained : — 

23rd August 1901, 3.50 p.m. Very fine weather; 
disappearance of the ultra-violet, beginning with the M 

30th August 1901, II a.m. Very fine weather; 
disappearance of the ultra-violet beginning with L. 

31st August 1 90 1, 3 p.m. Very hazy weather, sky 
entirely clouded ; no disappearance of the ultra-violet. 

26th October and 12th November 1901, 2 p.m. Fine 
weather ; disappearance of the ultra-violet beginning 
with M. 

It will be seen from the above that if the eye, instead 
of being sensible to the radiations going from the A to 
the H rays, were sensible only to the radiations going 
from H to U, we should find ourselves, now and then, 
though in full sunshine, plunged in darkness. 


The ultra-violet possesses, according to my experi- 
ments, so special and so energetic an action that it 
must be supposed to have an active part in the 
phenomena of nature. It is to be desired that regular 
researches should be instituted in observatories on its 
presence and its disappearance in the light. In con- 
junction with this, studies might be made on the 
variations of the infra-red, for which I have shown there 
exists a re-agent — sulphide of zinc with green phosphor- 
escence — as sensitive as gelatino-bromide is for visible 
light. The invisible spectrum has, it is well known, 
a much greater extent than that of the visible spectVum. 
It is probable that its really very easy study might raise 
meteorology from the wholly rudimentary state in which 
it still is at the present day. 

IdefiHty of the Products of the Dissociation of Bodies by 
Light with those derived from Radio-active Substances, — 
I have always upheld the analogy of the effluves of 
dissociated matter as shown in the foregoing experi- 
ments with those emitted by spontaneously radio-active 
bodies. Lenard and Thomson have, since my researches, 
made this identity indisputable, by demonstrating their 
derivation by a magnetic field, and by measuring tlie 

ratio — between the charge of the particles and their 

mass. This ratio has been found to be identical with 

that observed with the cathode rays, and the particles 

of radio-active bodies. The condensation of water 

vapour by the particles of matter dissociated by the 

influence of light — which produces, as we know, cathode 

rays — has likewise been obtained by Lenard. 

Photographic Action of the Particles of Bodies dissociated 
by Light, — The study of this photographic action caused 
me in the past a great loss of time ; I abandoned it 


because, in reality, by reason of its irregularity, it 
does not constitute a process of measurement, while the 
electroscope affords a precise one. I will only say that 
when a sensitized glass plate, enclosed in an envelope 
of black paper and covered by some object or other, is 
exposed — well protected from all light — to the effluves 
of a metal struck by the sun, there will be obtained, 
after fifteen minutes' exposure, the outline of the object 
placed on the black paper. 

With metals exposed directly to the sun the impression 
on the photographic plate is sometimes intense, some- 
times nil, and is too uncertain, in short, to provide a 
scientific means of investigation. 

1 have always observed, besides, that after a certain 
exposure to the sun, a metal generally loses the property 
of giving photographic images, even when a sensitized 
plate is exposed in the dark, directly on the surface of 
the insolated metal, instead of being placed beneath 
it. This phenomenon occurs, as I shall show later, 
through the metal exhausting rapidly, under the in- 
fluence of slight heat, the provision of radio-active 
emanation it contains, which is only formed again very 

Diffusion of the Effluves proceeding from the Dissociation 
of Bodies hy Light, — One of the most curious properties 1 
have noticed in these effluves is the rapidity of their 
diffusion, which enables them at once to pass round all 
obstacles. This diffusion is so considerable that, in the 
experiments given above, the plate of the electroscope 
may be placed behind the metallic mirror, entirely hidden 
by it, and consequently protected from all light, without 
the discharge being suppressed. With a mirror of 
aluminium it is only reduced to a seventh of what it 
was previously. If the electroscope be placed laterally 
beside the mirror o that its extreme edge is i cm. 


Within the vertical line of its edges, the discharge 
is hardly reduced by one-tenth. If the electro- 
scope be removed to 10 cm. from the same edge of 
the mirror, the discharge is only reduced by three- 
quarters. The effluves, consequently, have entirely 
gone round the obstacle formed by the mirror. No 
doubt the propagation has partly been effected by the air, 
and also by the sides of the mirror itself, to which the 
dissociated particles seem to adhere and to slide along 
unless they are stopped by a non-metallic surface. This 
can be proved by the following experiment which 
succeeds very well in the sun : — 

. A strip of aluminium of which the face is intentionally 
well oxidized to render it inactive, and the other face 
cleaned with emery-paper is placed above the electro- 
scope (Fig. 47), so that the cleaned face shall alone be 
struck by the light and shall project effluves on to the plate 
of the electroscope. The discharge of the instrument 
corresponds under these conditions to 20"* in 15 seconds. 
The strip of metal is then turned round, so that it is the 
oxidized face which faces the electroscope, and the 
cleaned face is towards the sun. The effluves produced 
can then only act on the electroscope by passing round 
the strip. Now, the discharge is still 5** in 15 seconds. 
Without changing anything in the above arrangement, a 
band of black paper two centimetres in width is gummed 
on to the borders of the non-oxidized face towards the 
sun. This band prevents the passing round of the 
particles, and the discharge of the electroscope ceases. 

Metals struck by light for the most part retain a 
small residual charge, which allows them to slightly 
discharge the electroscope in the dark for a few minutes. 
It therefore suffices to expose to the sun a cleaned piece 
of metal, and to place it in the dark above the electro- 
scope, for a slight discharge to be produced for a few 


Mechanism of the Discharge of Bodies electrified ly 
the Particles of Dissociated Matter. — The mechanism of 
the discharge of bodies electrified by the effluves of 

Fig. 44. — Mechanism of Ihe discharge a/ an cttetrostopi by the 
effuvti Bf /he diumaltd mailer dittngagzd /rem Ike me/ah 
struck by solar light. — The strip of metal placed on an insu- 
lating support is connected w[th an uncharged electroscope by 
a cotiducting wire, and placed aliove a charged electroscope. 
The apparatus being eicposed to sotai tight, the effluves diseii- 
piged render the air a conductor. The result is that -the 
charged electroscope discha^es itself while the other 
becomes charged. This occurs as if the Iwo electroscopes 
weie connected by a wire. 

dissociated matter by light, by the gases of flames, 
by the emanations of radio-active bodies, or, by the 
cathode rays, is always the same. All of them act by 


rendering the air a conductor. Fig. 44 and the above 
explanation makes the mechanism of their action quite 

Transpareficy of Matter to the Effluves of Dissociated 
Atoms, — Do the particles of dissociated matter pass 
through material objects? We know that this is the 
case with the ^ rays of radium, but not with the a rays 
which form 99% of the emission and are stopped by a 
thin sheet of paper. How do matters stand with the 
particles of bodies dissociated by light? 

It appears easy, at first sight, to verify the phenomenon 
of transparency. As we possess a reagent sensitive to 
certain radiations, we interpose between it and these 
radiations, the body of which we wish to test the 
transparency. If the effect be produced through the 
object, we shall say the body has been transpierced. 
Nothing is more simple in appearance, and nothing 
more erroneous in reality. 

It sometimes happens, in fact, that a body appears to 
have been transpierced when this has not been at all 
the case. It may have simply had its flank turned, which 
is exactly what happens in the case of very diffusible 
bodies, as was shown in the last paragraph, or as 
happens in the case of radiations with great wave-length 
— the Hertzian waves, for instance. It is this apparent 
transparency which formerly deceived physicists as to 
the supposed transparency of conducting and insulating 
bodies to electric waves. This transparency was 
admitted till the researches I carried out with Branly ^ 
proved that mountains and houses were passed by going 
round and not through them, and that if metals seemed 
to be transpierced, it was because the Hertzian waves 
passed through the cracks of the boxes which seemed 

^ Set forth in the Comptes rendus dc V Academic des Sciences, and in 
the Revne ScrentifiqHe, 1899. 


to be hermetically closed — and, in fact, were so to 

The apparent transparency may also be the conse- 
quence of the fact that when one face of a body is 
struck by a radiation there is produced, by a kind of 
induction, an identical radiation on that part of the 
other face whi^h corresponds to the point struck. J.J. 
Thomson has^ maintained that this was precisely the 
case with the cathode rays, and Villard believes it to be 
the same with metals which are acted on by the radia- 
tions of radium. The photographic impression through 
a metal would be the simple consequence of a secondary 
emission on the posterior face of the strip opposite to 
the point struck. 

We have a rough example of what happens in these 
various cases by taking, for instance, the propagation 
of sound. A person shut up within a completely closed 
metal chamber will hear very clearly all the musical 
instruments played outside that chamber. The vibra- 
tions of the air which produce the sound appear thus to 
pass through the metal. We know, however, that it is 
not so, and that the air which strikes the metal walls 
simply causes them to vibrate. The vibrations on one 
of the faces of the metal are propagated to the other 
face, which in turn causes the air in contact with it to 
vibrate. The vibrations seem thus to have passed 
through the metal, which, notwithstanding, is abso- 
lutely opaque to the air. 

A like reasoning, however, may perhaps be applied to 
all forms of the transparency of bodies. We might 
even include the case of transparency to light, could this 
hypothesis be easily reconciled with the phenomenon of 

However this may be, the complete solution of the 
problem of transparency is difficult, and the single fact 
that eminent physicists have been unable to agree on 


the transparency of bodies for the cathode rays and for 
the emanations of radio-active bodies is sufficient to 
show the difficulties of the question. All we can say 
about an apparently transparent body is that things 
occur exactly as if it were transparent. 

In the case of the effluves from matter dissociated by 
light, the problem is further complicated by the extreme 
diffusion of these effluves, which enables them, as we 
have seen, to go round objects. To simply interpose a 
strip of metal between the'effluves and the electroscope 
would lead to very erroneous results. It would require 
to be of excessively large dimensions, which would not 
be very workable. 

To prove the transparency — or, if it be preferred, the 
equivalent of transparency — it is necessary that the 
body one wishes to work with should be surrounded 
by an enclosure shut up on all sides. This I was able 
to obtain by means of my condensing differential elec- 
troscope, thanks to which it has been possible to study 
the transparency of bodies for the effluves emitted by 
light, by radio-active bodies, by the gas of flames, by 
chemical reactions, etc. Its use has permitted us to 
verify apparent transparency; but in further studying 
the phenomenon, I was led to recognize, as will be 
detailed later on, that all bodies contain an emanation 
similar to that belonging to spontaneously radio-active 
bodies, which appears to be the cause of the actions 

Elimination of Canses of Error, Influence of the 
Hertzian Waves accompanying the Electric Sparks used to 
produce the Ultra-violet, — All the experiments described 
above are extremely easy of repetition when made with 
the sun. There are only two precautions to be observed 
in this case. The first is to clean vigorously with emery- 
cloth every ten minutes the metal operated on, an 


operation not required when using the ultra-violet rays 
obtained by means of electric sparks ; the second consists 
in replacing the ordinary knob of the electroscope, with 
which the charge is insignificant, by a copper plate 
about io<^"^in diameter. It is quite unnecessary to 
clean this latter. 

The importance of a large receiving surface is para- 
mount, and it is because many observers have neglected 
this essential point that they have been unable to repeat 
my former experiments. 

When we have to do with very refrangible radiations, 
which do not exist in the solar spectrum at our alti- 
tudes, and can only be produced by means of electric 
sparks, the experiments become much more delicate; 
and if certain precautions are not taken, we are exposed 
to the causes of error I now point out. The most 
important consists in the action of electric influences 
capable of discharging the electroscope. Doubtless it 
suffices to hide the light of the s:parks with black paper 
to be able to see if all discharges are suppressed, which 
is not the case when electrical influences supervene. But 
when one notices that these last are produced, it is not 
always an easy matter to suppress them. 

The means generally employed to eliminate them con- 
sists in covering the quartz window of the spark-box with 
fine transparent wire gauze let into a frame made of a 
large strip of metal and connected with the earth, but this 
means is not always sufficient. Invariably exaipining 
after each experiment whether the action on the electro- 
scope ceased when the light was covered up with black 
paper, I several times perceived rapid discharges due to 
electrical influences. As they did not act equally on both 
the positive and the negative electricity with which the 
electroscope was charged, but only on one of them, I 
conceived the idea of getting rid of them by connecting 
with the earth, without any change in the rest of th«i 


arrangements, one or other of the coatings of the Leyden 
jars employed according to the direction of the discharge 
observed. This means always succeeded. 

What is the origin of the electrical influences which 
are formed round the sparks of the electrodes, and of 
which physicists have often pointed out the existence 
and the effects without ever attempting to determine 
their nature ? Not being able to find any hints on the 
subject, I was led to inquire of what they consisted. 
They are simply very small Hertzian waves. It was 
difficult to anticipate this, for they were not supposed 
to be produced by discharges between points. 

Their existence is proved, either by the illumination 
at a distance of a Geissler tube (which necessitates 
working in the dark) or, better, by using a coherer 
in circuit with an easily working bell and a battery. 
This apparatus, which may remain fixed, as shown 
in several of the figures, immediately reveals to 
the ear, by the ringing of the. bell, the formation of 
any Hertzian waves which may interfere with the 

By bearing in mind the researches I made together 
with Branly, on the enormous diffraction of the Hertzian 
waves which permits them to travel round all obstacles, 
and on the passage of these waves through the smallest 
crevices, it will be understood that it is very difficult, 
notwithstanding all possible precautions, to avoid their 
influence when they form. They must therefore be 
prevented from forming. Here are, from my obser- 

^ The Hertzian waves can not only discharge an electroscope, 
whether charged positively or negatively, but likewise recharge it 
again, sometimes positively, sometimes negatively, provided it be not 
placed beyond about a metre from the source of the waves. This can 
be verified by placing the electroscope at a distance of one metre from 
a Righi radiator and covering up the light of the sparks with a large 
sheet of black paper. 



vations, some of the conditions in which they are 
generated: — 

Hertzian waves manifest themselves when the spark- 
box is not carefully insulated from its support by a 
coating of paraffin. They also manifest themselves 
when the electrodes are too far apart, and especially 
when their points are blunted, which happens when 
they have been working for some time. The Hertzian 
waves which then form are very small and are hardly 
propelled farther than 50 to 60 cm., but they are 
sufficient to disturb the experiments. They disappear 
as soon as the extremities of the electrodes have been 
filed to very sharp points. 

There exist other causes of the production of Hertzian 
waves in these experiments, but to enumerate them 
would carry us too far. With the arrangement I have 
described and figured in the plates, the operator will 
always be warned of their presence. 

Among the causes of error which I must point out, 
there is one which has never, to my knowledge, been 
mentioned anywhere, and is of considerable importance, 
I refer to the superficial alteration in a strip of quartz 
exposed for less than a quarter of an hour to the 
sparks of the electrodes. It becomes covered with an 
almost invisible layer of particles of dust which suffice 
to render it opaque to the ultra-violet rays of a length 
inferior to 0.250/x. When quartz thus altered is used, it 
is as if use were made of a strip of thin glass, opaque, as 
we know, to the extreme ultra-violet ; and all the effects 
observed are falsified. This cause of error, which 
occasioned me much loss of time, is very easy to avoid, 
since it is sufficient to wipe the quartz with fine linen 
cloth every ten or fifteen minutes. 

All these causes of error may also have an influence 
on the so-called negative leak which we shall shortly 
St udy. 


Interpretation of the Preceding Experiments, — We have 
already interpreted the experiments set forth in this 
chapter, and shall simply recall the fact that aH the 
products of the dissociation of bodies by light are 
identical with those obtained from radio-active sub- 
stances. There is the same deviation of the particles 

• e 
by a magnetic field, the same ratio — of the mass to the 


electric charge, etc. 

But how are we to explain this dissociating action of 
a weak ray of light on a rigid metal ? The explanation 
is not easy. I shall confine myself to reproducing that 
given by Professor de Heen in his memoir, Les Ph&no^ 
mknes dits cathodiques et radio-actifs : — 

** When a luminous ray falls on the surface of a 
metallic mirror, the ions vibrate in unison with part or 
the whole of the radiations striking it. Therefore, 
during the action of this radiation, a superficial pellicule 
of infinitesimal thickness vibrates with the frequency 
of certain oscillations of the source itself. In the case 
of luminous and ultra-violet radiations, this surface 
actually corresponds to an excessive temperature im- 
perceptible to the touch, because, its thickness being 
very slight, the quantity of heat confined in this pellicule 
is entirely negligible. 

** Now, if this is so, the metallic surface, subjected to 
a luminous and, more especially, to an ultra-violet 
radiation, will be traversed in all directions by currents 
which we shall term high frequency currents. 

**The ions will be subjected to such repellent actions 
that they will jump. Thenceforth the surrounding space 
will be subject to ionic projections, or radiations, 
similar to those noticed in vacuum tubes. 

**Such is the interpretation of the fundamental fact 
discovered for the first time by Gustave Le Bon, which 
will be found at the basis of this new chapter in physics. 


This physicist thenceforth supposed that this mani- 
festation belonged to an order of natural phenomena 
absolutely general. It was this idea, much more than 
the admirable experiment of Rontgen, which decided 
me to take up the study of electric phenomena." 



The idea that radio-activity is due to chemical reactions 
led me to search for the means of rendering artificially 
radio-active bodies which are not so. In this case we 
are quite certain that the presence of radium, uranium, 
or Other similar substance counts for nothing in the 

It will be seen later on that various chemical re- 
actions, such as hydration, can produce this radio- 
activity. I shall now show that bodies presenting only 
traces of radio-activity under the influence of light, such 
as mercury, can, on the other hand, become extremely 
radio-active. It is suflicient to add to this metal a (n»\(T>th 
of its weight in tin, a body which is no more radio-active 
under the influence of ordinary light than mercury. 
With this proportion of tin, mercury is sensitive only 
to the solar ultra-violet from X = o.^6ofi to A^o.agS/x; 
but if the proportion of tin be increased to i%, the 
mercury is dissociated by most of the rays of the visible 

It was interesting to compare the radio-activity 
artificially given to a body with that of spontaneously 
radio-active bodies such as thorium and uranium. The 
experiment being very important, I will simplify it to 
such a degree that it can be easily repeated at a lecture. 




The first thing is to determine the degree of dissocia- 
tion of a body by light, and then to compare it with that 
of a spontaneously radio-active substance — a salt of 

uranium, for instance. We 
shall see that the dissocia- 
tion provoked by light is 
much more important. 

A strip of tin is taken, 
ID cm. square and 2 cm. 
thick. Its borders are 
fastened by means of four 
narrow bands of gummed 
paper to a cardboard screen 
of the same size, and the 
whole is plunged for twenty- 
four hours into a bath of 
mercury, wiping oif from 
time to time the layer of 
oxide formed on the sur- 
face. The strip thus pre- 

^ ^ . ^ , , pared, which the cardboard. 

Fig. 45. — Comparison of the ats- . ^ - , , . ... 

sociaiion of spontaneously radio- Prevents from breakmg, will 

active bodies and of metals under indefinitely retam its radio- 

tke influence of light,— A. tin activity under the influence 

mirror prepared as described in of light SO long as its sur- 

the text and a screen of the same f^ce is very slightly wiped 

size coated with oxide of thorium .,, ., / e ,• 

or of uranium are used alter- ^'^h the finger from time 

nately. The dissociation of the ^^ time. 

atoms of the tin under the influ- This done, the experiment 

ence of light is forty times more is arranged as indicated 

rapid than that of the radio-active /pj ^ jj^^ electro- 

bodies just mentioned. • . , .. i 1 j 

scope is inductively charged 

by an ebonite rod ; its charge is, in consequence, 


By arranging the strip of tin so that the sun may 

strike its surface, it will be noticed that the gold leaves 


draw together in a few seconds. With a diffused 
light, the discharge still takes place, but more slowly. 

Having noted the number of degrees of discharge in 
a given time, the experiment is commenced anew with 
a screen covered with a salt of uranium, prepared in 
the following manner: — 

Nitrate of uranium is pounded in some bronzing 
varnish, and spread on a cardboard screen of exactly 
the same size as the strip used in the preceding ex- 
periment (10 cm. X 10 cm.). If this screen be 
arranged, and the electroscope charged as previously 
indicated (Fig. 45), a discharge of about 6" in 60 
seconds will be noted. By operating in the sun with 
a mirro^ of amalgamated tin placed at exactly the same 
distance from the electrpscope, it was shown that this 
latter discharged itself at the rate of 40' in 10 seconds.. 
It is therefore seen that artificial radio-activity given to a 
metal hy light may he forty times greater than the 
spontaneous radio-activity possessed by salts of uranium. 
With oxide of thorium, approximate figures are ob- 
tained. If we suppose, with Rutherford, that i gramme 
of uranium emits 70,000 particles per second, it follow? 
that metals, which under the dissociating influence of 
light have an activity four times as great, would emit, 
surfaces being equal, nearly 3,000,000 particles per 



Since Hertz' experiments, it has been known that a 
conducting body electrified negatively loses its charge 
if it be subjected to the action of the ultra-violet rays 
obtained from electric sparks, and it is recognized in 
more recent works — 

I St. That this leak can only take place under the 
influence of the ultra-violet light; 2nd. That it is the 
same for all metals ; 3rd. That the discharge only takes 
place when the charge of the metal is negative^ and not 

Elster, Geitel, and Branly, it is true, mentioned 
some time ago two or three metals which discharged 
in ordinary sunlight, and the last-named cited several 
bodies which show the positive leak ; but these pheno- 
mena were considered as exceptional and as in no wise 
possessing a general character. 

As the subject did not appear to me exhausted, I 
deemed it well to take it up anew. Although there is 
a certain difference between the phenomena of the 
discharge of a body already electrified and that of the 
production of effluves emanating from an unelectrified 
body and capable of acting on an electrified one as 
shown in the preceding chapter, yet the two phenomena 

^ "The ultra-violet rays only act when they meet with a surface 
positively electrified." — Bouty, 2nd Supplement to the Physique of 
Jamin, 1899, p. 188. 



have the same cause — namely, the dissociation of matter 
by light. No experimenter had suspected this cause 
before my researches. 

The experiments I am going to set forth prove — ist, 
that the so-called negative leak is also, though generally 
in a lesser degree, positive ; 2nd, that the discharge 
takes place under the influence of the various regions 
of the spectrum, although the maximum occurs in the 
ultra-violet ; 3rd, that the discharge is extremely 
different in the various bodies, the metals especially. 
These are, as will be seen, three propositions exactly 
contrary to those generally received and recapitulated 
above. Now for the justification of them. 

Method of Observation, — For studying the negative 
leak in solar light the method of observation is quite 
simple, since we have only to place the body, the 
discharge of which is to be observed, on the plate of 
the electroscope, and it charges itself at -the same time 
as the latter. This charge is given by influence either 
by a glass or an ebonite rod, according to the sign of 
the charge desired. Care must be taken that the gold 
leaves are the same distance apart in all cases. 

When it is desired to study the discharge produced 
by the ultra-violet rays beyond the solar spectrum, 
recourse must be had to the special arrangement 
shown in Fig. 46. 

The bodies to be studied are fixed in a clamp replacing 
the ball of the electroscope. They become charged 
with electricity at the same time as the latter. The 
light is supplied by aluminium electrodes connected 
with the coatings of a condenser kept charged by an 
induction coil giving sparks of about 20 cm. The 
electrodes are placed in a box with a quartz window 
covered over with wire gauze framed in a sheet ot 
metal and earthed. 


Fir, 46 -^Apparatus (mployid for the study of the iiaL tinder 
uUrs Violet hgkl of electrified lioditi —The coil used for the 
production of the spaik is not shown in tlic Fig Un ihe 
right IS seen the bell and coherer which reveal Ihe pro- 
duction of Hertzian waves capable of disturbing Ihe 


The distance at which the electrified body is placed 
from the source of light plays, at least for very re- 
frangible rays, a most important part, and it is useful 
to mount the electroscope, as I did, on a graduated 
bar which allows its distance from the source of light 
to be regulated. 

When one wishes to separate the various rays of the 
spectrum, one works, as 1 said before, by means of 
various screens interposed between the source of light 
and the electroscope, and the transparency of the 
screens is determined by the spectrograph. 

When the experiments are made in the sun, the 
plates of metal must be very frequently cleaned with 
emery-cloth (every ten minutes at least), but as we 
advance into the ultra-violet this cleaning becomes of 
less importance. It is no longer every ten minutes, 
but only once every two or three days that it needs 
repetition. With so long an interval when operating 
in the sun, the discharge would not be entirely sup- 
pressed, but would become more than a hundred times 
less. For the light from electric sparks, the omission 
of the cleaning only reduces the discharge by a half or 

1 have, however, succeeded in forming alloys re- 
quiring, for experiments in the sun, no cleaning and 
preserving their properties for about a fortnight, with 
the simple precaution of passing a finger on their 
surface, from time to time, in order to clear away the 
dust or the slight layer of oxide which may have 
formed. The best are strips of amalgamated tin 
prepared as directed in a former paragraph. 

Negative Leak in the Light of the Sun, — The following 
table shows the rate of discharge in light of a strip of 
metal 10 cms. square placed on the plate of the 
electroscope. This rapidity is calculated from the time 


necessary to produce a discharge of 10 degrees, the 
maximum of rapidity being represented by 1000. 

Rapidity of the negative leak in the solar light. 

Amalgamated tin - - 1000 

Amalgamated zinc - - 980 

Aluminium recently cleaned - 800 

Amalgamated silver - - 770 

Magnesium recently cleaned 600 

Zinc recently cleaned - - 240 

Amalgamated lead - - 240 

Cadmium - - - - 14 

Cobalt 12 

Gold, steel, copper, nickel, 
mercury, lead, silver, phos- 
phorescent sulphides, car- 
bon, marble, wood, sand, 

etc. ----- 2 (maximum). 

All these bodies discharge themselves when charged 
positively, but in the light of the sun the leak is 
throughout very weak (i degree at most in i or 2 
minutes). It increases greatly when the light of the 
sun is replaced by the light from electric sparks, but 
its maximum is no way produced, as is the case with 
the negative leak, by the radiations of the end of the 
spectrum. The fact is proved by this very simple 
experiment. A thin strip of glass one-tenth of a mille- 
m^tre thick which considerably retards the negative 
leak in many cases when placed before the source ot , 
light, has only a very feeble diminishing action on 
the positive leak. The radiations which produce the 
negative leak are^ therefore^ not the same as those pro- 
ducing the positive leak. 

Leak with Bodies charged with either Sign in the 
Electric Ultra-violet Light, — Substances in strips are 


arranged as before, or, what comes to the same thing, 
are fixed vertically on the electroscope by a clamp as in 
Figure 46. The source of light (electric sparks) is 
placed at 20 cm. from the body on which it is to act. 
The tables below give, for this distance, the intensity of 
the discharge of the bodies charged either negatively 
or positively under the light from electric sparks. The 
greatest negative leak corresponds to 6° per second 
(360** per minute) ; the slowest to J° per second (30** per 
minute). For the positive discharge it is much weaker, 
since it varies between 7" and 16° per minute. Taking 
1000 as the maximum rapidity of leak, the following 
figures are obtained: — 

I St. Negative leak in the ultra-violet light of electric 






- 1000 





- 680 





- 610 

Red copper 




- 390 





- 340 





- 270 

Tin - 




- 270 





- 240 





- 210 





- 200 

Steel (polished) 



- 80 

2nd. Positive leak under the same light. — The dis- 
charge of the electroscope varies from 16° per minute 
in the case of nickel, zinc, and silver to 7° in that of 
steel. There is, therefore, no question of an insig- 
nificant discharge, but of a really very important one. 

The above figures represent the leak produced by the 
totality of the luminous radiations given by the sparks 
proceeding from aluminium electrodes. 


From the foregoing we may conclude that all electric 
fied bodies exposed to the ultra-violet light are subject to a 
negative or positive leak without any other difference than 
that of intensity. 

Far from being identical in all bodies^ as was asserted 
up to the presenty this leak varies considerably according 
to the bodies employed. 

Sensitiveness of various Bodies to the Different Regions of 
the Ultra-violet, Elimination of Causes of Error, — The 
rapidity of the discharge of divers bodies varies greatly 
with the several regions of the spectrum, as may be 
gathered from the hints in a preceding paragraph. 
Some, such as aluminium, zinc, etc., are sensitive to 
the regions of the visible solar spectrum ; others, 
such as nickel, steel, platinum, etc., are only sensitive 
to the extreme region of the ultra-violet of the electric 
spectrum: which is why a simple plate of glass, one- 
tenth of a centimetre thick, placed before the quartz 
window of the spark-box stops all discharges for the 
nickel series, but stops only a part of the discharge 
produced by the other. 

The figures given above show that there is a pre- 
dominance of the negative leak over the positive for 
good conducting bodies — that is to say, metals. It is 
otherwise with bad conductors — such as wood, card- 
board, paper, etc. For these latter the positive dis- 
charge, as pointed out by Branly, may become equal 
to the negative discharge, and even exceed it. But we 
must here take account of two sources of error which 
appear to have escaped former observers. 

The first, already mentioned, is the state of the 
quartz. If not cleaned every lo minutes it absorbs 
the extreme region of the ultra-violet, and as this 
absorption does not prevent the positive leak produced 
by less refrangible regions, the negative discharge will 


436 diminished, and, consequently, may appear the same 
as or less than the positive leak. Such would be the 
case with a metal much oxidized or covered by a greasy 
body which is sensitive only to the extreme regions of 
the ultra-violet. 

The second cause of error is the considerable influ- 
ence of distance. The most extreme regions of the 
spectrum are most active on the negative discharge, 
while they have a rather weak action on the positive. 
Being absorbed by the air in an increasing degree as its 
density increases, it follows that their effect on the 
negative discharge becomes slower as the distance from 
the source of light is increased. Thus, at 25 cm. 
fro,m the spark, the positive discharge of wood will be 
double the negative discharge; at 8 cm. it is the other 
way — the negative leak will then be four times greater 
than the positive. The paramount importance of dis- 
tance in these experiments is therefore obvious. To 
this should be added that at a short distance the dis- 
sociation of the gases of the air begins to manifest 
itself; — a matter 1 will go into later. 

Having made these reservations, I give here the 
positive and negative discharges observed in some of the 
bodies in which experiments were made at a distance of 
25 cm. 

1 give the figures of the discharges in degrees of the 
electroscope per minute, without bringing them to 1000, 
as in the preceding experiments: — 

Various woods (deal, teak, plane) 

Yellow cardboard 


It will be seen that for several of the bodies on which 
the experiments were made, the positive discharge was 



discharge discharge 



T minute. 

I minute. 




1 6' 




markedly superior to the negative discharge. The rays 
which produce the negative discharge on these various 
bodies have a wave-length under 0.252/4, and it suffices 
to suppress them from the spectrum for the negative 
charge to be likewise suppressed. 

The sensitiveness of black bodies, especially lamp- 
black spread on a strip of cardboard, is considerable. I 
have obtained 61° of negative discharge per minute, at 
a distance of 25 cm., from the spark; but at 10 cm., 
it rises to figures which would represent 300' for the 
same length of time (figures approaching the sensibility 
of the most sensitive metals). With the same variations 
in distance, the positive leak only increases from 7** to 


12 . 

Influence of the Nature of the Electrodes, — The nature 
of the electrodes employed to produce the electric sparks 
has a considerable influence, as already stated, and this 
influence is not the same for the positive as for the 
negative discharge. The following table gives the leak 
per minute, calculated from the number of seconds 
necessary to produce 10° of discharge, with electrodes 
of various metals acting by the light they produce on a 
strip of electrified zinc connected with the electroscope*: — 

Aluminium electrodes 



per minute. 




per minute, 

1 8* 













According to the electrodes used, the negative 
discharge may, it will be seen, vary from single to 
double, and the positive discharge from single to triple. * 
I have already shown that this phenomenon is not due 


to the length of the spectrum of the metals, since that 
of gold goes as far as that of aluminium. 

By comparing the various tables published in this 
work, it will be seen that the leak produced by solar 
light is far different from that resulting from the action 
of electric light. This is due solely to the fact that the 
spectrum of the light from electric sparks is much 
further extended into the ultra-violet than that of the 
solar light. 

It is easy to give to the electric spectrum properties 
identical with those of the solar spectrum, by arresting in 
the former case the rays which do not exist in the latter. 
All that is required for this, is to replace the quartz in 
front of the sparks by a glass plate 0.8"* thick. This 
stops all radiations which do not occur in the solar 
spectrum — that is to say, those exceeding 0.295/4. It 
is then noticed that metals which, like copper, produce 
a very rapid discharge in the electric light and hardly 
any in the sun, become insensible to the electric light; 
while metals like aluminium, which produce a discharge 
in the sun, continue to produce it in the electric light. 

Divers Influences able to vary the Leak of Electricity 
under the Action of Light. — Several causes, in addition 
to those mentioned already, also cause the leak of 
electricity to .vary under the action of light, notably of 
that of the sun. As in order to study these variations a 
body with a constant sensitiveness was required, I made 
use of plates of amalgamated tin as before mentioned. 
This substance is extremely active, but only attains its 
maximum of intensity after an exposure of some minutes 
to the light, a fact precisely contrary to what is observed 
in various metals, especially aluminium and zinc. 

The best of all bodies with a constant sensitiveness, 
if its manipulation were not so inconvenient, is mercury 
containing a small proportion of tin* With uAoth of 



its weight in tin, it is, as I have said, only sensitive to 
the advanced regions of the solar ultra-violet — that is, 
beyond about the ray M. By increasing the proportion 
of tin to Ttfvth, it becomes sensitive for a far more ex- 
tended region of the spectrum. 

Continuous researches for eighteen months with plates 
of amalgamated tin proved to me that the sensitiveness 
of metals to light — that is to say, the time taken by 
them to lose the electric charge they have received — 
varied not only with the hour of the day, but also with 
the season. The figures I first gave several years ago, 
having been taken in winter and in very cold weather, 
were too low. 

The discharge is always less rapid in winter than in 
summer, but during the same day it may vary in the 
proportion of i to 4. It diminishes rapidly as the hours 
progress. For instance, on the 9th August 1901 the 
discharge, which at 4.30 p.m. was 50° per minute, fell to 
16* at 5.50 p.m. On the 24th August 1901, the discharge, 
which was 80' per minute at 3.25 p.m., fell to 40" at 
4.30 o'clock. For several days I followed, hour by 
hour, the variations of the leak, and drew up tables of 
them. There would be no interest in publishing them, 
for the differences do not depend on the hours, but 
mainly on the variations of the solar ultra-violet, 
which often disappears in part (from M, and even from 
L) under the influence, as I have already stated, of 
causes totally unknown. 

Clouds do not sensibly reduce the discharge, which 
remains about the same as in the shade. Nor does 
their presence noticeably reduce the solar ultra-violet, 
which I have been able to photograph through fairly 
thick clouds. 

Dissociation of the Atoms of Gases in the Extreme Region 
of the Ultra-violet, — We have just seen that all bodies, 


simple or compound, conductors or insulators, sub- 
jected to the action of light undergo dissociation. 
But among none of the bodies examined up to now 
do gases appear. Are we to suppose that they escape 
the common law ? 

This exception seemed improbable. Yet up to 
Lenard*s last researches the dissociation of gases by 
the action of light had not been observed. No doubt it 
was supposed that the discharge of electrified bodies, 
when struck by light, might be due to the action of 
the luminous rays in the air, but this hypothesis fell 
to the ground in face of these two facts — first, that 
the discharge varies according to the metals, which 
would not be the fact if it were the air and not the 
metal which was acting; and second, that the dis- 
charge takes place still more rapidly in a vacuum than 
in the air. 

The reason of this apparent indifference of gases, air 
especially, to the light which strikes them is very 
simple. Some metals are dissociable only in. a very 
advanced region of the ultra-violet. If gases should 
happen to be dissociable only in still more advanced 
regions, th^ observation of their dissociation must be 
difHcult, seeing that the air with slight density is as 
opaque as lead for the radiations of the extreme ultra- 

Now, as Lenard has shown, ^ it is solely in this 
extreme region of the ultra-vidJet that what was then 
called the ionization of gases, which is no other than 
their dissociation, is possible. He saw that it sufRced 
to bring the bodies under experiment to within a few 
centimetres from the source of light — that is, from the 
electric spark — for the discharge to be the same for all 

1 **Uber Wirkungen des ultra-violet ten Lichtes auf gasformige 
¥J6r^t** {Annakn der Physik, Bd. I., 1900). 


bodies,^ which shows that it is then the air which 
becomes the conductor and acts. It is light, and no 
other cause, which intervenes, for the interposition of 
thin glass stops all effect. 

By a special arrangement, which there would be no 
advantage in describing here, Lenard has measured the 
wave-length of the radiations which produce the ioniza- 
tion of the air. They begin towards o.iSofi — that is to 
say, just at the limits of the electric spectrum as 
formerly known (0.185/*), ^"^ extend as far as o. 140/X.2 
The discovery of these short radiations is, as is 

^ In a former memoir Lenard asserted that the nature of the charge 
was indifferent, and even gives this fact as new : '' Das aber positive 
Ladungen in Licht fast ebenso schnell von der Platte verschwinden, 
stimmt nicht mit Bekannten flberein** (**Uber Wirkungen des ultra- 
violetten Lichtes, in Annalen der Pkysikj 1900, p. 499). 

In a subsequent memoir (same publication, vol. 3, p. 298) Lenard 
indicates, contrary to his first assertion, that the positive is superior to 
the negative charge. In his first experiments there must have arisen- 
causes of error, such as the production of Hertzian waves, which the 
eminent physicist subsequently eliminated. 

'^ The production of these very refrangible rays seems due partly to 
the tension of the current which produces the sparks. Lenard, whose 
memoir is very summary, gives no details on this point, and confines 
himself to saying that he added to the Leyden jars a very large coil 
fitted with a Wehnelt interrupter. The influence of this coil is very 
evident from the fact that it increased the effect fivefold by modifying 
the primary, but he gives no further details save those indicated in this 
three following lines : — 

*'Hierin konnte zunachst Vorteil erzielt werden durch Anbrigung 
einer zweckm'assigeren Prim'arwickelung im Inductorium, es verfiin- 
flfachte dies bisher in Luft erreichte Entfernung" (p. 491). 

The tension of the sparks cannot be the sole factor to be noticed. I 
have considerably increased it by the well-known Tesla apparatus, but 
without obtaining any greater advantage than a slight increase in the 
positive and a slight decrease in the negative discharge. The contra- 
dictory results in the nature of the discharge noted by Lenard in his 
two memoirs and those repeatedly noted by myself seem to indicate 
that the action of causes yet unknown is at times superposed on that of 
known actions. 


known, due to Schuman. By creating a vacuum in a 
spectrograph, he proved that the ultra-violet spectrum, 
which, from the incorrect measurements of Cornu and 
Mascart, were believed to be limited to 0.185/*, in 
reality extended much farther. He has succeeded in 
photographing rays reaching as far as o. loofi. It is 
probably the absorption exercised by the gelatine of the 
sensitive plates, and no doubt also by the material of 
the prism, which prevents further progress. 

As we advance into the ultra-violet spectrum, all 
bodies, the air especially, become more and more 
opaque to the radiations. It would therefore be very 
surprising if the X rays, which pass through all bodies, 
were constituted by the extreme ultra-violet, as some 
physicists have maintained. 

Most bodies, including air of a thickness of 2 cm. and 
water of a thickness of i mm., are, in fact, absolutely 
opaque for these radiations of very short wave-length. 
There are hardly any transparent to them except quartz, 
fluor spar, gypsum, and rock salt, and even these only 
on condition of their surface not being roughened. 
Pure hydrogen is equally transparent. 

The extremely refrangible radiations of light therefore 
dissociate, not only all solid bodies, but also the particles 
of the air they pass through, while radiations less 
refrangible possess no action on gases, and^ only dis- 
sociate the surface of the solid bodies they strike. 
These are two very different effects which may be 
superposed on each other, but which will not be con- 
fused if it be borne in mind that when it is the air that 
is decomposed, the nature of the metal struck and the 
state of its surface ^re points of no importance ; while 
the leak varies considerably with the metal when it is 
the latter that becomes dissociated. Besides, the influ- 
ence of the extreme ultra-violet can be almost entirely 
avoided by removing the source of light to a little 


distance, since a layer of air of 2 cm. suffices to stop 
this region of the spectrum. If, therefore, the sparks 
from the electrodes are at several centimetres from the 
quartz window of the spark-box, no effect due to the 
decomposition of the air can be produced. 

In comparing some of the experiments set forth so 
far, it will be noticed that those bodies which absorb 
most light are precisely those which are the most dis- 
sociable. For example, air which absorbs the radia- 
tions below 0.185/ii, is decomposed by these radiations. 
Lamp-black, which completely absorbs light, is ener- 
getically dissociated by it, and disengages effluves in 
abundance. This explanation does not appear at first 
sight at all to tally with the fact that metals which have 
recently received a mirror polish are likewise the seat 
of an extremely abundant disengagement of effluves. 
The objection vanishes, however, when it is considered 
that polished metals which reflect visible light very w^ell 
reflect very badly the invisible light of the ultra-violet 
extremity of the spectrum, and absorb the greater 
part of it. Now, it is precisely these absorbable and 
invisible radiations which produce most effect. 

To give a clear idea of the properties of the various 
parts of the ultra-violet spectrum, I will put them in 
tabular form. It shows that the aptness of light to 
dissociate bodies increases with every step into the 

The Property of DissoctaHng Matter possessed by the 
various Parts of the Ultra-violet Spectrum, 

From 0.400/i to 

These radiations pass through ordinary glass. 
They can only dissociate a small number of 
metals, and even then only if they have 
been recently cleaned. 



The Property of Dissociating Matter possessed by the 
various Parts of the Ultra-violet Spectrum — continued. 

From 0.344/A to 

From 0.295/A to 

From 0.2 5 2M lo 

0.1 COM 

The ultra-violet of this region only passes 
through glass not thicker than 0.8™™. After 
0.295/A, it is completely absorbed by the 
atmosphere, and consequently plays no part 
in the solar spectrum. This region, though 
much more active than the preceding one, 
has still only a rather weak dissociating 
activity on most bodies. 

The ultra-violet of this region is not met with 
in the solar but only in the electric spectrum. 
It can only pass through glass plates not 
exceeding 0.1™™, in thickness. Its dis- 
sociating action is much more intense and 
more general than that of the preceding 
region of the spectrum, but much less than 
that of the following region. It dissociates 
all solid bodies, but has no action on gases. 

This region of the ultra-violet is so little pene- 
trating that air, as soon as the radiations 
of 0.185M are reached, is as opaque to it 
at a thickness of two centimetres as metal. 
A glass plate one-tenth of a millimetre thick 
stops this extreme ultra-violet absolutely. 

The dissociating power of this region is 
much greater than that of the other parts of 
the spectrum. Starting from 0.185/i, it 
dissociates not only all solid bodies, metals, 
wood, etc., but also the gases of the air on 
which the preceding region of the spectrum 
had no action. 

To sum up, the more we advance into the ultra- 
violet — that is to say, the shorter the wave-lengths of 
the radiations become, the less penetration these 



radiations have ; but their dissociating action on matter 
shows itself more and more energetically. At the 
extremity of the spectrum all bodies are dissociated, 
including gases, on which the other parts of the 
spectrum have no action. The dissociating action of 
the various luminous radiations is therefore in inverse 
ratio to their penetration?- 

The law thus formulated was quite unforeseen pre- 
vious to my researches. All earlier observations 
seemed to show that the rays at the ultra-violet end 
of the spectrum possessed so slight an energy as to 
be almost inappreciable by the most delicate thermo- 
meters. It is, however, these radiations which most 
quickly dissociate the most rigid bodies, such as steel, 
for example. 

^ These experiments on the electrical charges induced by ultra-violet 
light have been lately repeated in precise and careful fashion by Sir 
Wm. Ramsay and Dr. Spencer. The results are given in the Philo- 
sophical Magazine for October 1906, to which the reader is referred. 
— F. L. 



General Action of the Gases of Flames on Electrified 
Bodies. — If feeble chemical reactions, such as a simple 
hydration, can, as we shall see later, provoke the 
dissociation of matter, it is conceivable that the 
phenomena of combustion which constitute intense 
chemical reactions must realize the maximum of dis- 
sociation. This is, in fact, what is observed in the 
gases of flames, and has led to the supposition that 
incandescent bodies give forth into the air emissions of 
the same family as the cathode rays. 

For at least a century it has been known that flames 
discharged electrified bodies, but no pains whatever 
were taken to search for the causes of this phenomenon, 
although it was one of primary importance. 

The first precise researches on this subject are due to 
Branly. It is he who pointed out that the active parts 
of flames are the gases emitted by them. He also 
studied the influence of temperature on the nature ot 
the discharge. Using as a source of radiation a platinum 
wire made more or less red hot by an electric current, 
he noted that at a dark red the negative discharge 
was much higher than the positive discharge, while at 
a bright red heat the two discharges were equalized, 
which would seem to prove that at diff*erent tempera- 
tures ions are formed charged with diff*erent electricities. 
Figures 47 and 48 show modes of very easily proving 



the emission, during combustion, of particles with the 
power of rendering air a conductor of electricity. With 
a flame placed at lo cm. from the electroscope (Fig. 47) 
a very rapid discharge (60° in 30") is obtained. With 

Fjg. 47. — Apparatus for shmoing the leak of tkctricily uudtr the 
influence of /lames according lo the distance and the nature of the 
body en which the cKtian is frodwed. The charged strip on 
the electroscope draws lo itself the ions of contrary sipi which 
discharge it. 

an ordinary candle in a closed lantern with an elbowed 
chimney placed at 13 cm. from the electroscope (Fig. 
48) the discharge gives 18° in the same space of time. 


At 30 cm. it falls to 4°. The extreme diffusion of the 
ions in the air explains these differences. 

After passing through a long cooled tubular worm, 
according' to the arrangement represented in another 
chapter (Fig. 52), the gas from the flames still produce, 
though feebly, a discharge of the electroscope. 

Fig. 48. — Apparatus showing visibly Ike ele<tric leak under the 
action of Ike particles of dissociated mattet contained in the 
gases of the flames. 

I have already recalled to mind that the recent experi- 
ments of J. J. Thomson have shown that an incandescent 
body is a powerful and unlimited source of electrons — 
that is, of particles identical with those of radio-active 
bodies. He has proved it by the fact that the relation 
between their electric charge and their mass is the same. 


The phenomena of combustion therefore constitute one ot 
the most energetic causes of the dissociation of matter. 
They produce such an enormous quantity of effluves 
from dissociated matter that it is possible to hope that 
some means of utilizing them may be discovered. 
Meanwhile, these effluves diffuse themselves in the 
atmosphere, where they play some part not yet known 
to us. 

Properties of the Particles of Dissociated Matter con- 
tained in Flames, — I have noticed in my experiments 
three curious facts which have not been pointed out 
before. The first is the property possessed by the 
elements of dissociated gas of traversing, in appear- 
ance at least, metallic receptacles; the second is the 
increasing rapidity of the discharge according to the 
thickness of the metal connected with the electroscope ; 
the third is the loss rapidly undergone by several 
metals of the property of being influenced by the gases 
of flames. 

The electroscope is charged as directed in a former 
paragraph, and the lamp for the purpose of producing 
dissociated gases is arranged as shown in Fig. 49. 
There will be then noticed a rather rapid discharge at 
the beginning of the experiment, which soon becomes 
slower and then stops. The metal does not regain its 
sensitiveness by being cleaned, but only after a prolonged 
repose of at least twenty-four hours. The figures 
below give an idea of the variations thus observed. 
The source of light was placed at such a distance 
as to obtain a rather slow discharge, so that the 
differences could be noted: — 

Discharge during the first three minutes 9** 

next three minutes 4° 

following three minutes 2* 



We shall see on interpreting this last phenomenon, 
that it is due to an emission of radio-active emanation 
analogous to that of radium, but very quickly exhausted 
and very slowly renewed. 

But a part of the discharge seems certainly produced 
by the transparency of the metal forming the Faraday's 

Fig. 49. — Apparatus showing the action of dissociated mcUter 
contained in the gases of flames on an electrified body con- 
tained in a metal cage. —The effect produced is as if the 
metal cage were rapidly transpierced by the dissociated 
matter. When it is desired to entirely eliminate the 
action of heat, the gases are made to pass through a worm 
2 metres long immersed in a reservoir of water (Fig. 52). 
They then only reach the electroscope after complete 
cooling, and still produce a slight discharge. 

cage, since it manifests itself, though in a slight degree, 
with gases completely cooled so as to eliminate the 
action of heat. 

When working as indicated in Fig. 49, it suffices to 
place the extremity of the elbowed chimney of the lamp 


at 2 or 3 centimetres from the cylinder forming the 
Faraday's cage to obtain a discharge of from 7° to 10'' 
per minute. This continues for about ten minutes, and 
then stops entirely. It is useless to clean the cylinder; 
it must be allowed to rest for several days. The 
alteration is spread over the whole circumference of the 
cylinder and not solely on the part exposed to the gases 
of the flames. It is due, I repeat, to the emission of a 
radio-active matter similar to the emanation of radio- 
active bodies.^ When working with gases cooled by 
their passage through a worm, as shown in Fig. 52, the 
discharge does not exceed 2" per minute, and appears 
in that case to be due to the transparency of the metal. 

' It would be satisfactory to have this experiment checked by an 
independent observer. McLennan and Burton {Phil, Mag.^ Sept. 
1903) have shown that if a cylinder of any metal is enclosed within a 
second one of the same material insulated from it and surrounded by 
air, it gradually acquires a negative charge. So C. T. R. Wilson 
{Proc. Roy, Soc, vol. 69, pp. 55 el seq,) asserts that there is a con- 
tinuous production of ions in air contained in a closed vessel, even when 
it is not exposed to any known ionizing agent. — F.L. 




I HAVE discovered a large number of chemical reactions 
producing the dissociation of matter. This is revealed 
by the characteristics which prove this dissociation — 
that is, the power of rendering the air a con- 
ductor of electricity, and in some cases of producing 

To establish the fact of this dissociation, instead of 
working by the method shown in Fig. 36, it is simpler 
in the case of merely qualitative experiments to place 
the body under study on the plate of the electroscope, 
which is then charged (Fig. 50). 

Here are a few examples of reactions accompanied 
by the dissociation of matter : — 

Dissociation of Matter by the Hydration of certain Salts, 
— Among the various reactions I formerly pointed out 
as accompanied by radio-activity is the hydration of 
sulphate of quinine. This body, as has long been 
known, becomes phosphorescent by the action ot 
heat ; but what was not known, is that when it has 
lost its phosphorescence after sufficient heating, it 
suddenly becomes brightly luminous and at the same 
time radio-active on cooling. After searching for the 
cause of these two phenomena I found that they were 
due to a very slight hydration. The radio-activity only 
manifests itself at the beginning of the hydration and 




lasts but a few minutes. The phosphorescence, on the 
other hand, persists for a quarter of an hour. 

This property of sulphate of quinine — viz., that of 
becoming phosphorescent by cooling — is quite contrary 

to what is observed in the 
many other phosphorescent 
bodies which never phos- 
phoresce as they cool. 

In order to realize the 
experiments of phosphor- 
escence by refrigeration and 
radio-activity in sulphate of 
quinine, it should be heated 
to i25°C. on a metal plate 
till all phosphorescence has 
completely disappeared. 
When removed from the 
^ plate on which it was 
heated, the sulphate of 
Fig. so,—Siudy of the Dissoci- quinine again becomes phos- 
aiion ofMatur by Chemical phorescent as it cools, and, 
Keaciions,—Tht bodies cap- ^ . . , , 

able of producing the dissocia. P^^^^^ ^^ ^"^^ ^" ^^® P^^^® 
tion of matter by their re- of the electroscope, gives 

actions are introduced inio for three or four minutes 
the receiver placed on the an abundant disengagement 
plate of the electroscope; ^f effluves, which cause the 
this latter is then charged and . r 1 • 

its discharge watched. This ^^^^^^ of the mstrument to 
arrangement is much more collapse (12" during the first 
simple than the classic method minute, 4" in the second), 
indicated in Fig. 36, and gives The amount employed in 
a^ good results when quaniita-'^ experiments was about 
tive ones are not required. r < 1 n 

2 grammes of sulphate of 

quinine. The cessation of the phosphorescence -occurs 
long before the disappearance of the discharge. The 
two phenomena are therefore independent of each 


From the measurements kindly made for me by 
M. Duboin, Professor of Chemistry at the Facultd des 
Sciences of Grenoble, the absorption of i milligramme 
of water vapour is sufficient to render phosphorescent 
and radio-active i gramme of dried sulphate of quinine. 

The foregoing experiment can be repeated indefinitely. 
When the sulphate of quinine is hydrated it simply 
has to be heated anew. It becomes phosphorescent by 
heat, is extinguished, and shines afresh and becomes 
radio-active in the course of cooling by hydration. 
Since hydration and dehydration are the causes of the 
phosphorescence of sulphate of quinine, we can, by caus- 
ing it to be hydrated or dehydrated by means other than 
heat, obtain the same phosphorescence. Introduce into 
a wide-mouthed bottle some sulphate of quinine with a 
little anhydrous phosphoric acid, and cork the bottle. 
The phosphoric acid will at once deprive the sulphate 
of quinine of its moisture. One has only to open the 
bottle and blow into the interior to see the sulphate of 
quinine become quickly phosphorescent. On closing 
the bottle again the salt of quinine dehydrates itself 
anew, and the same operation can be repeated numbers 
of times. 

Sulphate of cinchona gives the same results as 
sulphate of quinine, but the phenomena, especially that 
of phosphorescence, are less intense. 

Dissociation of Matter during the Formation of various 
Gases, — Among the great number of reactions pro- 
ducing dissociation of matter I will also cite the 
following : — 

Formation of oxygen by the decomposition of oxygenated 
water by means of dioxide of manganese, — The products 
are placed in the metal capsule on the plate, which is 
then charged (Fig. 50). The reaction lasts a little over 
a minute. The leak of the electroscope is about 9°. 



Formation of hydrogen by the decomposition of water by 
means of the sodium amalgam, — Operation as before. 
Loss, 9° per minute. The discharge is exactly the 
same whether the electroscope be charged positively 
or negatively. The decomposition of water by sulphuric 
acid and zinc gives the same results. 

Formation of acetylene by the action of water on corbide 
of calcium, — The same operation. Loss, ii** per 

Formation of ozone, — Air charged with ozone by 
means of a large coil and an ozonizer is directed by 
a bellows on to the plate of the electroscope. The loss 
is very slight, hardly 1° per minute, if the instrument be 
charged negatively, and 4° if charged positively. 

It would be tedious to multiply these examples. The 
dissociation of matter is observed in many reactions, 
and especially in hydrations. Oxidations, even the 
most energetic (oxidation of sodium in moist air, for 
instance), have generally little or no action. 

To close this branch of the subject I will merely cite 
the dissociation of matter during the oxidation of phos- 

Dissociation of Matter during the Oxidation of Phos- 
phorus, — Phosphorus is one of the bodies with the most 
intense radio-activity. To prove this, phosphorus may 
be rubbed with a damp leather^ then placed on the 
electroscope and a discharge of 80*" per minute (calculated 
on the loss in 20 seconds) will be observed, whatever be 
the sign of the charge. The amount used is i centi- 
gramme of phosphorus. When the leather becomes dry 
the discharge stops almost entirely. Red phosphorus 
and sesquisulphide of phosphorus have no action. 

The phosphorescence of phosphorus is due to causes 
as yet not clearly defined, which do not seem to be 
confined solely to oxidation and hydration. By very 



carefully drying the phosphorus by means of the 
apparatus (Fig. 51), the phosphorescence is extremely 
slight, while it becomes very vivid under the influence 
of a trace of water vapour. 

The numerous memoirs published during the last 

CfftjttuUimtm^ -^ 

Fig. 51. — Apparatus of Gustave Le Bon and Martin^ used for 
determining the part played by water vapour in the phosphor- 
escence of phosphorus, — The two compartments A and B 
being supplied with anhydrous phosphoric acid, phosphorus 
is introduced into A, then A and B are separated by 
tightening the screw V. The phosphorus absorbs the 
oxygen of A, shines and then becomes extinguished. The 
screw V is then loosened and the dry air from B penetrates 
into A. One observes only a very slight phosphorescence, 
confined to the surface of the piece of phosphorus. If 
then, by means of the funnel represented in the figure, a 
drop of water is allowed to fall into B, the small quantity of 
vapour it emits is enough to render the phosphorus much 
more brilliant and there will form round it a luminous 
cloud. Water vapour therefore ^lays a manifest part in 

century on this question have not yet elucidated the 
causes of the phosphorescence of phosphorus. Several 
authors assert that the phosphorescence will be main- 
tained in a current of pure hydrogen carefully freed from 
all trace of oxygen, but I have never observed anything 


of the kind in my experiments. The presence of air has 
always appeared indispensable. 

The experiments I carried out with the co-operation 
of M. Martin, engineer to the great phosphorus works 
at Lyons, have given the following results : — 

ist. In the barometrical vacuum phosphorus is never 

2nd. In an atmosphere of carbonic acid gas, dry or 
saturated with water vapour, phosphorus does not 
shine. If into the globe of carbonic acid gas containing 
phosphorus a simple bubble of air be introduced, this 
bubble becomes instantaneously phosphorescent. 

3rd. Phosphorescence in moist air is not accompanied 
by the production of phosphuretted hydrogen. 

4th. During phosphorescence there is a production of 
ozone revealed by the blue coloration of iodine paper. 
To remove all doubts as to its presence, we deprived the 
air of the ozone it might normally contain, by passing 
it through two bottles, one containing mercury, the 
other protochloride of zinc. Thus deprived of its 
natural ozone, as is evident by the absence of any 
coloration of the iodine paper, the air comes .to 
phosphorus which has been dried at 200** C. in a 
current of carbonic acid gas. The iodine paper becomes 
quite blue as soon as the air has passed through the 
globe containing the phosphorus. This latter has 
therefore the property of transforming the oxygen of 
the air into ozone. 

In a recent study effected at Professor J. J, 
Thomson's laboratory, which was published in the 
Philosophical Magazine of April 1905, under the title of 
** Radio-activity and Chemical Change," Mr. Norman 
Campbell contests my conclusions on radio-activity 
from chemical reactions. He does not deny the 
discharge observed on the electroscope, but he attributes 
it to the action of the heat produced by various reactions. 


He admits, however, being unable to explain how heat 
can produce the leak of electricity observed.^ 

I have never dreamed of disputing the influence of 
heat, of which I have explained the effects by 
showing that it acted by expelling the provision of 
radio-activity which the bodies contain ; but it is very 
evident that its intervention cannot be claimed in 
chemical reactions which are unaccompanied by any rise 
in temperature, such as the hydration of sulphate of 
quinine during cooling, the oxidation of phosphorus, 
etc. On the other hand, there are reactions accompanied 
by a rise in temperature, such as the oxidation of 
sodium, which produce no radio-activity. The influence 
of heat and that of chemical reactions constitute two 
factors whose action is very distinct though at times 
they may be superposed, 

^ The mistake made by Mr. Campbell was shown in the Athenceum 
of 24th March 1906. — F L. 



The experiments which follow were made at the outset 
of the discovery of the radio-active bodies in order to 
prove that their dissociation, contrary to the opinion 
then current, depended upon certain chemical reactions 
of a nature unknown indeed, but resembling those 
which produce phosphorescence. 

The phenomena of radio-activity — that is, the emission 
of effluves — obtained with uranium, thorium, and radium, 
are very noticeably modified by heat and moisture. 
Prolonged heat at first excites radio-activity, which 
increases very much for a time but can then no longer 
be brought back to its primitive state excepting after 
long repose. As to hydration, it suppresses phosphor- 
escence and diminishes radio-activity. 

The diminution of the action on the electroscope by 
hydration varies greatly with the substances employed. 
I give the figures obtained with divers radio-active 
substances, first dried at 200" C, then pounded and 
mixed with their own weight in water — 


2 grammes of dried nitrate of uranium ... 26° in 10 minutes. 

Same quantity of hydrated nitrate of uranium 7",, 10 ,, 

2 grammes of dried red oxide of uranium ... 37° ,, 10 

Same quantity hydrated red oxide of uranium s° a ^^ 

2 grammes of dried oxide of thorium ... 45° ,, 10 

Same quantity of hydrated oxide of thorium 17° ,, 10 
2 grammes of dried bromide of radium of 

poor activity ... ... ... ... 30** ,, 5 seconds. 

Samequantity of hydrated bromide of radium 10° ,, 5 ,, 



I should add that if the water acts chemically, it at 
the same time acts partly by the absorption of a part 
of the emitted particles — that is to say, like a screen. 

Wetted, or simply exposed to moisture, radio-active 
bodies lose all phosphorescence, which is not at all the 
case with ordinary phosphorescent bodies, and they 
only regain it when brought to a white heat. 

Temperature also plays a considerable part in the 
phosphorescence of radio-active bodies. It suffices to 
heat salts of radium, to cause them to momentarily lose 
their phosphorescence. The necessary temperature 
varies according to the samples, which are evidently of 
a very variable composition. Some among them re- 
quire a temperature of 500° C, and the phosphorescence 
reappears so soon as the body cools. For other 
samples, a temperature of 225* C. is sufficient, and 
the body does not regain its phosphorescence when 
becoming cool, but only after some hours, and some- 
times even only after a few days. 

The preceding considerations deduced from the 
actions of heat and moisture apart, the following 
experiment would seem to indicate the existence of 
those new chemical combinations which 1 have ex- 
amined elsewhere, combinations in which one of the 
elements is in an infinitesimal proportion compared 
with the other. 

After having determined the radio-activity of 30 
grammes of chloride of thorium — which spread out on 
a metal receptacle 10 cm. square, and placed on the 
electroscope, give 9** of discharge per minute — we 
dissolve them in water, adding i gramme of chloride 
of barium, a body which possesses no radio-activity, and 
we precipitate the chloride in the state of sulphate by 
the addition of a small quantity of sulphuric acid. The 
product, weighing about 7 decigrammes, is collected 

in a filter. These 7 decigrammes placed on the plate 

• ' , , 


of the electroscope give 16" of discharge, when the 
utmost that should be obtained is 9°, since the activity 
extracted from the chloride of thorium cannot be greater 
than that which was found therein at first, if it is not 
a case of chemical reaction. The chloride of thorium 
remaining has only lost the half of its activity. 

I must point out, however, that no measurements of 
the radio-activity of bodies by the electroscope have any 
very precise quantitative value. I only draw conclusions 
from them with reserve, since I have noticed the extreme 
influence of the greater or less degree of division of the 
matter treated. I said above that the 7 decigrammes 
of precipitated matter had given 16'' of discharge, but 
the filter used, which no longer contained anything, 
unless it were the very fine matter adhering to its rims, 
gave 40° of discharge per minute on the electroscope. 
Yet it only contained at the most a few millegrammes 
of matter, though spread over a large surface. 

Still more simply can be shown the influence of the 
division of Aatter on its radio-activity by the following 
experiment: — i gramme of pure chloride of thorium is 
spread in powder on the plate of the electroscope and 
gives a discharge of 1° per minute. We dissolve this 
powder in 2 cm. cube of distilled water, and in this 
solution dip a piece of filtering paper 10 cm. square; 
we dry it and place it on the plate of the electroscope. 
The discharge rises to 70 per minute— that is, 7 times 
more than with the same product in fine and dry 
powder. When the same sheet of paper is folded 
over so as to reduce its surface, the discharge falls to 
3 degrees. 

The same phenomena are observed with uranium. 
Place on the electroscope a small block of metallic 
uranium weighing some 30 grammes. It gives 12* of 
discharge in 10 minutes. Take a third of the same 
block — that is, 10 grammes — reduce it to powder, and 


spread it over a metal receptacle lo cm. square placed 
on the plate of the electroscope. The discharge rises to 
about 28*" in ten minutes. #So, by the fact alone of 
increasing the surface of the radio-active body, a quantity 
of tl^e same substance three times less, gives a discharge 
twice as great. The discharge which radio-active bodies 
produce is therefore reduced in large proportions by 
diminishing the surface. 

This reduction is not, however, proportional to the 
surface. As soon as the layer of a radio-active body 
attains a certain thickness, fresh additions, which only 
increase this thickness, have no effect. It appears as 
if these bodies were capable of absorbing the radiations 
they themselves emit. 

50 or 25 grammes of thorium, spread thinly on a 
receptacle of the same dimensions (12x17 cm.) as 
before, so as to cover it entirely, give exactly the same 
discharge (12' per minute). 

These same c[uantities (50 grammes or 25 grammes) 
placed in a smaller receptacle, will only give a discharge 
ot 7* per minute. 


• - r* ^ 

• , • \ 


It was in gases that the dissociation of simple bodies 
was first observed, and that at a time when one hardly 
thought of speaking about the dissociation of atoms. 
The phenomenon was then called by the name of 
ionization. This term, in reality, should be considered 
as absolutely synonymous with that of dissociation of 
matter, as I have already stated. 

The products of the dissociation of the atoms of gases 
are of the same nature as those attained by the dis- 
sociation of other bodies, such as metals. The relation 
of their electric charge to their mass is always the same. 
Their properties only vary, as explained elsewhere, 
according to whether the ionization takes place under 
ordinary pressure or in a very rarefied gas as in that of 
a Crookes' tube. 

Ionizing a gas, or, in other words, dissociating it, 
consists in withdrawing from its atoms those elements 
known by the name of ions, some bearing a positive, 
others a negative charge. 

These ions of contrary signs are always equivalent in 
number, so that, as J. J. Thomson has remarked, the 
mass of an ionized gas, taken as a whole, betrays no 
electric charge. This statement is, besides, in con- 
formity with all our knowledge of electricity. It is 
impossible to produce an electric charge of one sign 
without creating at the same time an exactly equal 
charge of the other sign. When, for instance, an 



S a 

g S3 u 




electric fluid is decomposed by friction, each of the two 
bodies employed contains a quantity of electricity 
strictly equal to that of the other, but of contrary sign. 

An ionized gas, therefore, taken as a whole reveals 
no sign of electricity, but if it be directed between two 
parallel electric plates, one charged with positive the 
other with negative electricity, the ions of contrary signs 
are attracted by one or other of the two plates, and the 
neutralization of a part of the charge of the plates can 
be verified by means of an electrometer. 

What becomes of the positive and negative ions 
formed in a gaseous mass? An ionized gas ■ preserves 
its conductivity for some time, but it does not keep it 
for ever, and at last it becomes impossible to detect in 
it any electric charge. The conclusion is that the 
positive and negative ions have recombined to form 
neutral electricity.^ 

The rapidity of recombination of the ions appears 
to be proportional to the number of ions present, 
and that is why, in gases ionized by very active 
bodies, such as radium, it is very rapid. The re- 
combination of ions is rendered much more rapid by 
the presence of solid particles, as may be verified by 
blowing tobacco smoke between two metallic plates 
charged with electricity, with an ionized gas passing 
between them. 

It is generally supposed at the present day that all 
ions, whatever their origin, are alike, and this opinion 
is especially founded on the sameness of their electric 
charge. My experiments have led me to suppose, on 
the contrary, that the various ions ought to exhibit 
notable differences among themselves. 1 have ob- 
served, in fact, that the rapidity of their recombination, 
or rather, of their disappearance — not to prejudge any- 

^ See on this subject the researches of Mr. Kleeman, Phil, Mag,., 
April and October 1906. — F. L. 



thing — varies greatly with their origin. Here are, for 
instance, three cases in which, from my researches, ions 
behave very differently: — 

I St. lofis produced by combustion, — These can pass 
through a cooled metallic tube, 2 metres long, as is 
shown by the action 






they exercise on an 
electroscope placed at 
the extremity of this 
tube (Fig. 52), but a 
very thin layer of 
water stops them. 

2nd. Ions produced 
by certain chemical re- 
actions, — Of these .re- 
actions I shall only 
mention the formation 
of hydrogen by the 
action of sodium Fig. 53. — Recombination of the ions 
amalgam or water. obtained in the dissociation 0/ matter 

The ions obtained 
almost entirely dis- 
appear after passing 
through a few centi- 
metres of the tube 

(Fig. 53)- 

3rd. Ions produced 

by the oxidation of 
phosphorus, — By bub- 
bling through a bottle 
containing water, air 
which has passed 
through a globe con- 
taining finely divided 

fragments of phosphorus, it is verified by the action 
oi the air on the electroscope that all the ions have 

by chemical reactions, — A, bottle 
containing water and sodium amal- 
gam. CB, tube conducting the ionised 
gas on to the charged electro- 
scope D. The ions generated in this 
form of the dissociation of matter 
neutralizing each other very quickly, 
it is sufficient to give a certain length 
to the lube CB for the discharge of 
the electroscope to become, contrary 
to what is observed in the experiment 
in Fig. 52, almost nil. For this 
reason it is preferable to make use of 
the arrangement represented in Fig. 
50, for studying the dissociation of 
matter by chemical reactions. 


not been retained by the water, as was noticed in the 
case of those obtained in the previous operations. 

It will be seen by these three examples that ions may 
show real differences among themselves notwithstand- 
ing their indisputable analogies. 

The quantity of gaseous molecules capable of being 
ionized in a given mass of gas is relatively very small, 
however energetic may be the process of ionization 
employed. Were it otherwise, it would be easy to 
extract from atoms a colossal amount of energy. 
Rutherford calculates the number of molecules dis- 
sociated, or rather, having undergone a commencement 
of dissociation, at i in 100,000,000. This figure is 
arrived at in various ways, notably by verifying the 
number of drops of water which result from the con- 
densation of water vapour produced by the presence of 
ions. Though this figure may appear insignificant, the 
number of ions is still considerable by reason of the 
number of particles contained in a gas, which is esti- 
mated at 36,000 billions per millimetre cube. The 
cubic millimetre of a gas might therefore contain 360 
million particles having undergone a commencement 
of dissociation, although only one molecule in a 
hundred millions might be partly dissociated. 




The concatenation of my experiments led me to discover 
the existence in all bodies of an emanation similar to 
that of the radio-active substances, which shows that 
all bodies dissociate spontaneously. This is how I was 
led to this demonstration. 

With the object of studying the transparency of 
metals to particles of dissociated matter, whether by 
light or combustion, I made use of the condensing 
electroscope previously described — of an electroscope 
enclosed in a Faraday's cage, and I noticed an important 
discharge under the influence of a heat slight enough 
to raise the temperature of its walls by only some 30**. 

The first explanation obviously was that the metal 
cylinder was transparent to radiations. 

I now give the experiments that showed me that the 
principal cause of the phenomenon was not due to 
any transparency, but to an emanation from the metal 
identical with that observed in radio-active bodies, such 
as thorium, uranium, etc., which, some time after my 
researches (published in the Revue Scientifique^ 22nd 
November 1902, p. 650), J. J. Thomson discovered in 
all bodies.^ 

Let us again take in hand the apparatus (Fig. 49), 
which will enable us to verify the following facts : — 

If the discharge takes place from the exposure of the 

^ As mentioned in an earlier note, Professor J. J. Thomson does not 
admit this. He claims, on the contrary, that the emanation proved by 



instrument to the sun, it is only noticeable if the tem- 
perature of the sun is hig-h enough to heat the metal. 

With the ultra-violet light of electric sparks, so much 
more active than solar light, but which does not heat 
metal, the discharge is almost nil. 

In arranging the apparatus as shown in Fig. 49 for 
studying the action of heat, it will be found that after 
repeating the experiment five or six times, the metal, 
which at first gave a discharge of some 10* a minute, 
soon gives a very small one, then none at all, and 
only regains its properties at the end of a few days.^ 

If, when a cylinder is very active under the influence 
of the heat of the gases of the flame, the lantern be 
withdrawn, the discharge continues for two or three 
minutes, as if the interior of the cylinder contained 
something able to neutralize a certain quantity of the 
electricity with which the electroscope is charged. 

The action produced by heat can be easily separated 
from that due to the transparency of the metal to 
particles of dissociated matter. The action of ionized 
gases and that of heat are two independent effects 
which are superposed, but which it is possible to 
separate. A slight increase in temperature produces a 
fairly strong discharge. Gases cooled by their passage 
through a long worm produce on the contrary but a 
slight discharge. The metal, in this last case, acts as 
if it were transparent. The walls of the Faraday's cage 
employed in this last experiment were only 0.2 thick. 

him to exist in Cambridge tap- water and some other bodies may be due 
to the admixture of some radio-active substance. The alternative 
explanation of Elster and Geitel that all nature is exposed to the 
bombardment of a radiation from some unknown source, to which only 
rock-salt is impenetrable, should be borne in mind. (See their com- 
munication in Physikaliscke Zeitschrift^ loth October 1905.) — F. L. 

^ This is confirmed by Sir William Ramsay's experiments referred to 
above (p. 376). The explanation he gives of the phenomenon differs 
from that in the text. — F. L. 


It is possible even without the action of heat to 
verify in ordinary bodies the existence of a constant 
emanation from dissociated matter, though this emana- 
tion is extremely small in quantity. 

To cause it to be apparent, it is necessary to compel 
it to accumulate io a restricted space. It is sufficient 
for this to fold a sheet of metal so as to transform it 
into a small cylinder similar to the one which encloses 
the ball of the condensing* electroscope. The lower 
opening is then closed and it is left for eight days in 
darkness, and then — still keeping it in darkness so as 
to avoid any possible influence from light — it is placed 
on the insulating disc of the electroscope to examine its 
radio-activity. It will then be found, after having 
charged the whole system exactly as I have directed, 
that a discharge of i to 2 per minute is obtained. As the 
metal rapidly loses that which it has accumulated, the 
discharge soon ceases. Many bodies other than metals, 
a box-wood cylinder especially, produce the same 

The metal, after ceasing to act on the electroscope, 
has not on that account exhausted its provision of 
radio-activity. It has simply parted with the quantity 
it can emit at the particular temperature at which 
the operation was effected. But, as with phosphores- 
cent bodies or radio-active matter, it only has to be 
slightly heated to cause it to again yield a more con- 
siderable emission of active effluves. To produce this, 
simply proceed exactly as indicated in Fig. 49, but to 
avoid certain objections, replace the lantern containing 
a candle by a small mass of metal heated to 400° C. — 
that is, at less than red heat, and placed at 3 cm. from the 
Faraday's cage. Though the walls of the latter only 
become heated by radiation to about 35°C., it is suffi- 
cient to give a discharge of 5 or 6 degrees per minute. 
This discharge lasts 2 or 3 minutes, and stops when the 



metal has exhausted all its provision of radio-activity. 
It can afterwards regain this only by repose. 

It will be seen in all the preceding experiments that 
things occur just as if the metal contained a limited 
provision of something — acting exactly in the same 
way as the emanation of radio-active , bodies — which it 
can emit rapidly under the influence of heat, but can 
then only recuperate by repose. 

This theory of the disengagement, under the influence 
of heat, of efHuves of particles of dissociated matter, 
the elements of which are closely reformed by repose, 
has the advantage of assimilating all bodies to the 
substances called radio-active like thorium and radium, 
which seemed to constitute strange exceptions to 
ordinary rules. The only difference is that the 
emanations of the latter reconstitute themselves as fast 
as the loss occurs. In ordinary metals, on the con- 
trary, the loss is only very slowly repaired, whence 
arises the necessity of allowing the metal a certain 
length of rest. % 

These experiments in any case prove clearly the 
phenomenon of the spontaneous dissociation of matter. 
I repeat that J. J. Thomson arrived later at the same 
conclusion by a different method.^ 

Radio-activity is then an absolutely general pheno- 
menon whose study will certainly lead to important 
practical results.^ It is already considered that the 
hitherto inexplicable action of certain mineral waters 
may be due to their radio-activity. This radio-activity 
would seem to show that the interior of the globe is the 
seat of disintegrations of matter which are perhaps not 
unconnected with earthquakes in view of the immense 
energy which matter may liberate by its dissociation. 

* See notes on pp. 115, 148, and 399. 

^ M. le Prof. Garrigouy in his inaugural lecture, has described in too 
flattering terms the importance of my researches from the medical 
point of view. 




The division of matter, however far it may be carried, 
does not produce any effects like those of its dissocia- 
tion. This seemed evident a priorty but it was useful 
to verify it by experiment. 

The finest state of division in which matter is known 
to us seems to be that in which bodies emit odours. 
The olfactory sense is in that case much more sensitive 
than the balance of the chemist, since small quantities 
of odoriferous matter can perfume for a long time 
several cubic metres of air without any sensible loss of 
weight. ^ 

• However divided these particles may be, they have 
none of the properties of matter in a state of dissocia- 
tion, and, consequently, do not render the air a con^ 
ductor of electricity. I have experimented on the most 
odoriferous bodies I could find — iodoform, vanilla, and 
artificial musk especially. All one has to do is simply 
to introduce them into a metal receptacle placed on the 
plate of the electroscope. The latter is then charged, 
first positively, and then negatively. It is found that in 
both cases the discharge is nil. 

The particles which these bodies give off represent 
then a state of simple division, and in nowise a dis' 
sociation of matter. Ordinary matter, however divided 
it may be supposed to be, cannot be confused with 
matter whose atoms are dissociated. Vaporization or 
pulverization, which does not affect the atom, cannot 
prdduce the same effects as its dissociation^ 




The simple bodies chosen for experiment are mercury, 
magnesium, and aluminium, elements which in a 
normal state can form no combinations among them- 
selves. By subjecting them to certain conditions of 
shock or pressure, we shall compel them to form 
admixtures in which one of the elements shall be in- 
finitcsimally small compared with the other. This is all 
that is required for these metals to acquire entirely new 
chemical properties. 

Here is a table of the principal properties of these 
bodies in their ordinary state, and of these same bodies 
transformed : — 


Mercury, — Does not decom- 
pose water when cold, and 
does not oxidize in air. 

Magnesium. — Does not de- 
compose water when cold, 
and does not oxidise in air. 


Mercury containing traces of 
. Magnesium, — Decomposes 
water when cold, and is 
instantly transformed, when 
exposed to the air, into a 
voluminous dark powder. 

Transformed Magnesium, — 
Decomposes water when 
cold, but does not oxidize 
when dry. 





Aluminium. — Does not de- 
compose water when cold, 
and does not oxidize. Can- 
not be affected by sulphuric, 
nitric, or acetic acids. 


Transformed Aluminium, — 
Oxidizes instantaneously, 
if dry, and becomes covered 
with thick white tufts of 
alumina. Rapidly decom- 
poses water until the metal 
completely disappears and 
transforms itself into alu- 
mina. Is violently affected 
by sulphuric, nitric, and 
acetic acids. Possesses an 
electromotive force double 
that of ordinary aluminium. 

We will now examine in detail the transformations 
we have just briefly indicated. I give first the modus 
operandi of these transformations : — 

Transformation of the Properties of Mercury, — If a 
fragment of magnesium be placed in a bath of mercury 
the contact of the two metals may be maintained for 
any lapse of time without their combining. If roughly 
shaken in a bottle the magnesium is still unattacked. 
In their ordinary state, then, these metals refuse to 
combine, but we shall see that we have only to modify 
their usual physical conditions very slightly to enable 
them to join in very unequal proportions. 

To compel the mercury to dissolve a small quantity 
of magnesium, the intervention of a slight pressure 
alone is needed. This pressure constitutes one of 
those causes peculiar to the effect required, one of 
those appropriate reagents, of which I have several 
times pointed out the importance in this work. 


This pressure may be light but it must be continuous. 
To obtain it we have only to fill a tube with mercury 
and to close it with a cork having a strip of mag- 
nesium, carefully cleaned with emery-paper, passed 
through it (Fig. 54). By thus stopping the tube with 
the cork, the magnesium remains dipped in the mercury 
without being able to float on its surface. 
Subjected to this feeble pressure it is 
slightly attacked in a length of time vary- 
ing from a few minutes to a few hours, 
according to the quality 
of the metal and the per- 
fection of the cleaning. 
The properties of the 
mercury then become 
profoundly modified. It 
acquires the property, as 
^ curious as it was unex- 

Arraigetniut , , 

*, ^huh iki Pected, of appearing to 

ti-aHsforma- oxidize rapidly in dry air, 

lUn of the and it vigorously decom- 

froptrtit, cf poses water so soon as '''<'■ SS--^"^- 

mircurv 11 T - - j ■ -^ it- tatiliBti of water 

MMi „ " f '"""•'»" ■" '• (F«- „ ^r,ur, ,„. 

cambinaiioH, 55)- taining a iraee ef 

under the in- To verify the apparent ma^eiium. (In- 

ffuence of dry oxidation of the mer- slanlaneous pho- 

sligit pre,, cury it only has to be 'os'^ph.) 

sure, with poured into a recently cleaned glass. Its 
. surface is then instantaneously covered 

with a black powder which forms again 
every time it is wiped away. If not removed, the 
coating of oxide soon reaches the thickness of a centi- 
metre. This permanent oxidation continues for an hour. 
The oxidation of the mercury is, however, only 
apparent. It is not in reality the mercury which 
oxidizes, but the traces of magnesium contained in it. 


By oxidizing, the magnesium transforms the mercury 
into an impalpable black powder of considerable volume. 

To verify the decomposition of water by the mercury, 
it is poured into a glassful of this liquid as soon as the 
magnesium is taken out of it. The decomposition of 
the water is immediate. It becomes slower at the end 
of fifteen minutes, but lasts over an hour. 

The modilied mercury rapidly loses its properties 
when exposed to the air, but it may be kept indefinitely 
and retains its new properties by 
covering it with a thin layer of oil of 

Transformation of the Properties of 
Magnesium — If, in the last experi- 
ment, instead of a thin fragment of 
magnesium being placed in the mer- 
cury under pressure, a strip of a 
certain thickness — one millimetre, for 
instance — be introduced, it will be 
found, by taking out this strip at p,^ 56.-2V«»,- 
the expiration of two or three hours poiiHon ef vmitr 
and plunging it into water, that the by magneiium 
liquid is rapidly decomposed (Fig. canttdning trata 
56). The hydrogen of the water is "{."^"^J^; *J"' 
disengaged, and the oxygen combines lonraph ) 
with the metal to form magnesia. 
The operation lasts about an hour, and as in the case 
of mercury, at last stops. If, after having immersed 
the magnesium in water, it is withdrawn, its tempera- 
ture rises considerably and it oxidizes in the air. 

This oxidation of magnesium in the air is — contrary 
to what was observed with mercurj-, and contrary to 
what will be observed in aluminium — very slight and 
only shows itself when the metal is wet. Withdrawn 
from the mercury and dried at once with a dry cloth, 


it does not oxidize, but retains indefinitely, if kept in a 
very dry place, the property of decomposing water. 

In the preceding- experiments I have worked without 
the intervention of any reagent, simply by putting in 
presence of each other two metals which will not com- 
bine in the ordinary way, but which I have compelled 
to interpenetrate by the action of slight pressure. 
The operation requires several hours. It will only 
require a few seconds if I call in a reagent which by 
the sole fact that it attacks magnesium will diminish 
its resistance to the action of mercury. 

I now introduce into a large bottle a few centimetres 
cube of mercury, a strip of magnesium, and water con- 
taining 1% of hydrochloric acid, and roughly shake the 
bottle for lo seconds. I now withdraw the magnesium, 
wash it to quickly remove all traces of hydrochloric 
acid, dry it and throw it into a precipitating glass full 
of water. It will at once decompose this liquid. 
Taken from the bottle and poured into a glass full of 
water the mercury will likewise decompose that. 

Transformation of the Properties of Aluminium. — The 
experiments with aluminium are much more striking 
than those effected with magnesium. 

To generate immediately on the polished surface of 
an aluminium mirror a vegetation in thick tufts as white 
as snow, constitutes one of the most curious experi- 
ments in chemistry, and one of those which has most 
struck the learned persons to whom I have shown it. 
Its realization is very simple. 

It is possible, as with magnesium, to compel the 
mercury to act under pressure, but the action of impact 
is much more rapid. 

It is sufficient to introduce into a bottle containing 
a few centimetres cube of mercury some strips of 
aluminium polished with rouge or simply cleaned with 


emery, and then to roughly shake the bottle for two 
minutes.' If one of the strips then be taken out, 
carefully wiped, and vertically placed on a support, 
it will be seen to 
be almost instant- 
aneously covered 
with white tufts of 
alumina, which in 
a few minutes 
g^row to a height 
of I centimetre 
from the surface 
(Figs. 57 to 60). 
At the commence- 
ment of the ex- 
periment the tem- 
perature of the 
strip rises to 102° 

The above oxi- 
dation does not 
manifest itself if 
the aluminium be 
introduced into air 
or oxygen com- 
pletely dry. The 
presence of a small 
quantity of water 
vapour is therefore indispensable for the production of 
'the phenomenon. The alumina formed is, besides, 
always hydrated. 

' All the figures given by me in this book must be veiy exactly 
followed by any one wishing to repeat my experiments. The repeated 
shock) produced by the shaking tend to generate combinations which 
do not occur otherwise. It was by shaking a liotlle containing 
ethylene «nd sulphuric acid some 3000 times that M. Berihelot, as is 
welt known, obtained the synthesis of alcohol. 

Figs. 57 to 60. — Formation of tufis of 
alumina on strips oF alutninium covered 
with invisible traces of mercury. (In- 
IS photograph.) 


If, instead of placing the aluminium on a support, it 
is thrown into a vessel full of water immediately after 
taking it out of the mercury, it energetically 
decomposes the liquid and transforms 
itself into alumina. This operation only 
ceases when the aluminium is entirely 
destroyed, a complete destruction which 
never occurs with magnesium. A strip 
of aluminium i millimetre in thickness, i 
centimetre in width, and lo centimetres in 
length is entirely destroyed by oxidation in 
less than forty-eight hours. 
Fig. 6i.— As with the transformed mercury, it is 
Arrangement easy to preserve indefinitely in the modified 
ofiheexpeii- aluminium all its properties by simply 
ment which . . ... . . , c ■• r ,■ 

allow* US to """"ersmg it m a bottle of oil- of vaselme. 
give to a strip ^^ '^^^ °^ ^^^ minute quantity of mercury 
of alD minium, necessary to transform in so great a degree 
after its ex- the properties of aluminium may be gathered 
trerolty bw by putting into a precipitating glass filled 
touched mer- .J .■ .-„ . ^ ,. . - r „ 

., with distilled water, but containing a small 

cuiy, the pro- . ' , _ , . . 

periv of de- quantity of mercury, a strip of aluminium 
composi ng cleaned with emery and fixed in a cork, so 
water, and of that it can only touch the mercury with its 
iraniforming lower extremity (Fig, 61). After a few 
iiself entirely (,ours the water begins to decompose, and 
into alumina, ... . . . , 

even when ihe this decomposition, even after the mercury 
mercury is has been taken away, continues till the strip 
wiihdiawn has been eaten away for a length of 5 to 6 
alter the de- centimetres above the point in contact with* 
ccmposi.ionof j^ ^^ercury. 

the water has , , , ■' , , , , , 

commenced. '" ^"^^ experiment the action of the 

mercury has thus extended far beyond the 
part in contact with it. It may therefore be supposed 
that the mercury has travelled along the strip of 
aluminium by an electro-capillary phenomenon. The 


following experiment is free from this objection, and 
shows even more clearly the slight quantity of mercury 
necessafy to transform the properties of aluminium. 

Into a dry and very clean bottle is put a small quantity 
of pure distilled mercury; the bottle is shaken for one 
minute, then the mercury is poured out so that there 
remains no visible trace of it on its sides, which, more- 
over, will have kept all their transparency if the metal 
used was perfectly pure. The bottle has, nevertheless, 
retained traces of metal sufficient to transform the 
properties of aluminium. It is only necessary to wash 
it with water acidulated by one-fifth part of hydrochloric 
acid, to place in it a strip of aluminium, and to shake 
the bottle for thirty seconds to cause the strip to exhibit 
the properties of oxidation mentioned, although it is 
impossible to discover on its surface any trace whatever 
of amalgamation.^ 

The proportion of mercury necessary to produce the 
transformation of aluminium can be represented in 
figures. If, to a bottle containing water acidulated by 
one-fifth of hydrochloric acid is added a trace of bi- 
chloride of mercury so weak that the liquid only con- 
tains mhnth of its weight, and a strip of aluminium be 
inserted, and the bottle shaken for two minutes, the 
aluminium will have acquired all the properties I have 
indicated, although, as in the preceding experiment, 

^ As the conditions in which aluminium can combine with mercury 
without the intervention of any reagent may be met with in any labora- 
tory, I at first supposed that some of the facts I noted must have loRg 
" been known. After fruitlessly consulting the most accredited chemical 
treatises without finding anything but facts relating to the amalgamation 
of aluminium in the presence of bases, I made inquiries of the most 
eminent chemists, and notably of M. Ditte, Professor of Chemistry at 
the Sorbonne, and author of the most complete and recent work on the 
properties of aluminium. One and all answered that none of the facts 
I pointed out, neither as regards aluminium nor mercury nor mag- 
nesium, had before been published. 


there is no trace of amalg'amation visible to the naked 

The electro-motive force of the modified aluminium is 
more than double that of ordinary aluminium. With a 
couple formed of platinum, pure water, and ordinary 
aluminium the electro-motive force I found was 0.75 
volts. By replacing in the same couple the ordinary 
aluminium by the modified aluminium, the electro-motive 
force rose to 1.65 volts. 

The hydrogen which is disengaged during the de- 
composition of water by the modified aluminium renders 
the air a conductor of electricity, as may be verified by 
connecting an electroscope with a metal receptacle 
containing water and fragments of transformed alu- 
minium. The discharge of the electroscope is about 
the same whether its charge be positive or negative. 

In addition to these new properties of oxidizing when 
cold and of decomposing water exhibited by the alu- 
minium, it has also acquired the property of being 
affected by sulphuric, acetic, and nitric acids, which in 
general have no action upon it. 

To observe this new property the following pre- 
cautions should be taken: — For acetic acid, it is only 
necessary to use it pure and crystallizable ; for nitric 
acid, the metal drawn from the bottle of mercury must 
be plunged into the nitric acid of commerce. After a 
few seconds the metal is very violently attacked, its 
temperature raised considerably, accompanied by the 
disengagement of heavy russet-coloured vapour. The 
reaction is rendered less dangerous by adding to the 
nitric acid half its weight of water. 

If nitric acid pure at 40° were employed instead of the 
nitric acid of commerce, the aluminium would not be 

The difference of action by pure and impure nitric 
acid is not an isolated example. It has long been 


known that there is a difference in the action exercised 
on lead by pure and ordinary water. Pure water 
attacks it, whil^ ordinary water does not. It is 
sufficient to pour distilled water on recently prepared 
lead filings for the liquid to become tinted in a few 
minutes by the formation of oxide of lead. With 
ordinary instead of distilled water the liquid remains 
perfectly limpid. Ordinary water modifies the surface 
of the metal, and deposits on it insoluble carbonates and 

Sulphuric acid does not affect ordinary aluminium, as 
the chemistry books teach us; but it energetically 
attacks modified aluminium. Pure sulphuric acid is 
almost devoid of action. Sulphuric acid in twice its 
volume of water must be used. Once the action has 
commenced, enough water can be added to reduce the 
sulphuric acid to one-hundredth part. The reaction 
continues with almost the same vivacity. Sulphuric 
acid diluted to the one-hundredth degree, which has an 
action almost nil on aluminium not already attacked, 
has, on the contrary, a very great action as soon as the 
reaction has started. Consequently, it has the power of 
continuing but not of exciting it. 

The fact that sulphuric acid pure or diluted does not 
attack ordinary aluminium is taught in chemistry books, 
but it is not quite exact. Pure sulphuric acid, it is true, 
has no action, but with half its measure of water added 
it instantaneously attacks aluminium, though less 
energetically than in the case of modified aluminium. 
The verification of so simple a fact not being open to 
any misconception, it must be supposed that the 
divergence between what is written in the books and 
what is shown by observation is due to the chemists, 
who first studied the action of sulphuric acid on 
aluminium, making use of a metal containing foreign 
bodies which modern manufacture has succeeded in 


eliminating. Foreign bodies in aluminium greatly 
modify its properties. I have come across samples of 
impure aluminium with which I was unable to effect any 
of the preceding experiments. 

In his notable memoir on the properties of aluminium, 
M. Ditte had already shown that this metal could be 
affected by acids, but only by adopting certain devices. 
For weak sulphuric acid to act, a little chloride of 
platinum has to be added ; for nitric acid, a vacuum has 
to be made above the metal plunged into the acid. The 
attack, moreover, is very slow, and in no wise violent, 
as is the case with modified aluminium. M. Ditte 
has concluded, from his numerous experiments, that 
aluminium is a metal easily liable to .attack under many 
conditions, several of which are still undetermined. 
The fact appears indisputable. The Navy has been 
compelled to abandon the use of aluminium, and unleiss 
means be found to associate it with a metal able to 
modify its properties, it will be impossible to employ it, 
as has been proposed, for metallic constructions. 




I HAVE already given, in the body of this work, photo- 
graphs showing how varied are the equilibria which 
may be imposed on particles of dissociated matter by 
utilizing their attractions and repulsions, and it would 
be useless to return to the subject. I have likewise 
reproduced photographs showing that by increasing the 
speed of projection of these particles by a rise in the 
electric tension of the apparatus generating them, they 
may be made visibly to pass through material objects. 
This operation having great importance, I recur to it so 
as to fully describe the technique which I did not pre- 
viously go into. 

The apparatus used, represented in Fig. 62, is very 
simple, but the adjustment of the great solenoid serving 
to considerably raise the electric tension is rather 
delicate. The position in which one of the wfres 
starting from the small solenoid will give the maximum 
result — that is, a long sheaf of effluves round the ball 
terminal of the solenoid — has to be ascertained by 
repeated experiments. The coil used must give at 
least 30 centimetres of spark for the effects observed 
to be very clear* When the apparatus is properly 
regulated, there will be seen to issue from the terminal 
a sheaf of effluves having the exact appearance of the 



dotted rays reproduced in the sketch. These effluves 
possess the surprising property of traversing without 

Fig. 62.--I>iagrala aflktar- 
tangimatl for giving la Ihi 
iffiuvetprsdueedby parlUlts 
of dismciaied mailer luffi- 
cient lensien to enable them 
to pass through thin plaits 
of non - eonditding bodies, 
such as glait and ebvmle. 

A, induclion coil. It musl 
be able id give sparks of 
30 centimetTcs miaimum 

B, C, Leyden jars connected 
with the polcE al the cmI. 
Their iniernal coatings Me 
connected to two rods, a i, 
lermi natine with balU which 

apail, and between which 
the discharge takes place. 
£, smalE solenoid, connected 
with the two external coat' 
ings of the Leyden jats. 
H, large solenoid formed of 
coiled copper wire. 1( is 
connected with the sole- 
noid E by two wires, GF. 
The position of the wire G 
is invariable. That of the 
' wire F should be deier- 

mined by experiment until the maximuin of effluves in lufls at K is 

I, metallic rod fixi;<1 to the lirsl spire of the solenoid. At its extremity 

are formed the lufls capable of passing through opaque bodies. 
K, strip of glass ot ebonite through which Ihe lufis of effluves pass. 
lis thickness must not exceed ) millim' 

deviation thin strips of various bodies: ebonite, glass, 
etc., placed in their way. This effect can seldom be 


produced if the thickness of these strips exceeds half a 
millimetre. ^ 

The experience is very striking. The course of these 
rays can be followed with the naked eye, which would 
not be the case if it were a question of a secondary 
emission or of a phenomenon of condensation. 

1 know of no other experiment by which the visible 
passage of particles through a material obstacle can be 
verified. I need not recall the fact that an electric 
spark can very well pierce through a solid body, as can 
be verified by placing a strip of glass or of cardboard 
between the two poles of a static machine or of an 
induction coil. But then the object Is pierced, while 
in my experiment the effluves pass through it without 
piercing it. 

Mr. F. Legge has repeated this experiment with a 
Tesla transformer, surrounded by solid vaseline. Owing 
to the elevation of tension thus obtained, he has 
succeeded in compelling the effluves to pass through 
ebonite discs half-centimetre thick, while with the 
apparatus at my disposal they will not pass through 
strips thicker than half-millimitre.^ 

If the effluves, obtained as has been explained, are 
made to pass through a Crookes* tube without either 
metallic cathode or anode — that is to say, through a 
simple glass receiver iti which a high vacuum has been 

^ It should be noted that the substance to be traversed must be an 
insulator of electricity. I have myself used with success discs of glass, 
ebonite, sulphur, and shellac respectively, of ^-cni. in thickness, and a 
disc of paraffin wax of i cm. ; nor do I doubt that these thicknesses 
might be exceeded if the tension were sufficiently raised. — F. L, 

^ The apparatus employed by me consists of a transformer of the 
pattern designed by Elster and Geitel, and made by Ernecke of Berlin. 
The oscillatory discharge is given by two Leyden jars 40 cm. high, 
connected in parallel, discharging through a spark gap sheltered from 
the light of I cm., and fed by a very powerful induction coil with a 
spaik-lenglh of 35 cm.^F. L. 



created, a productiori of X rays will be obtlEiined in 
sufficient abundance to show clearly the skeleton of 
the hand on a screen of platino-cyanide of barium. 
This very unforeseen experiment has always surprised 
the physicists to whom I have shown it.^ 

^ By suspending above the apparatus an inverted glass funnel con- 
taining an inner funnel of thin copper foil from which a wire is run so 
as to make contact with the charging rod of an electroscope, it can 
be shown that these "effluves" are positively charged. That the 
discharge from the secondary coil of such a transformer as is mentioned 
in Note 2, p. 417, is positive, has been shown by the researches of 
Dr. von Wesendonk. — F. L. 



In a recent work M. Becquerel has given an historical 
sketch of the discovery of radio-activity, and has caused 
the passages relating to me to be reproduced in small 
volumes for popular use. He asserts therein that my 
experiments for the most part alFect a complication 
** which conceals the real cause of the phenomena 
observed." He concludes by saying, ** It is sufficient 
to read the publications of M. Gustave Le Bon in 
Comptes rendus \de PAcademie des Sciences] to be 
convinced that, at the time they were written, the 
author had no idea of the phenomena of radio- 
activity. " 

Evidently no one is going to verify the assertions of 
M. Becquerel in the Comptes rendus of this period 
(1896-97), but should any one do so, what would he 
learn ? 

He would learn that for three years, M. Becquerel 
took infinite pains, with multiple and varied experi'^ 
ments, to prove that the radiations emitted by uranium 
could be polarized, reflected, and refracted, and, con- 
sequently, were only, according to the definition of 
J.J. Thomson, ** one of the forms of light " — an opinion 
which M. Becquerel himself acknowledged later to be 
entirely erroneous. The idea M. Becquerel himself 
entertained at that time was therefore as ine:k;act as 



In papers published by me at this very period, I upheld 
an opinion diametrically opposite to his. I laboured, in 
fact, to prove, contrary to his assertions, that the 
radiations of uranium could not be reflected, refracted, 
nor polarized. They, therefore, had no relationship 
to light, and constituted in my ideas a new form of 
energy very much akin to the X rays. I added that 
the uranium rays were identical with the effluves 
emitted by all bodies, under the influence of light. 
Time has proved the correctness of these various 
assertions, which I was then alone in maintaining. 

The historical sketch of M. Becquerel thus constitutes 
a complete inversion of the most evident facts, and, 
were I inclined to make use of the expressions he uses 
with regard to me and the first experiments on the 
phenomena afterwards termed ** radio-activity," I have 
the right to say that it was he, at that time in question, 
who **had no conception of the phenomena of radio- 
activity." But since the text of the Comptes rendus 
of the Acaddmie des Sciences are referred to, I will 
quote them. 

All the experiments of M. Becquerel tending to prove 
that the rays emitted by uranium refract, reflect, and 
polarize, are described therein most circumstantially 
and in detail. He proves the refraction of the uranium 
rays by means of a mirror, and their polarization by the 
classic process of tourgialine plates with crossed axes. 
These various experiments he checks one by the 
other, and on three different occasions repeats his 
assertions, each time bringing forward new demon- 
strations {Comptes rendus^ 1896, pp. 561, 693, 763). 
His last controlling experiment was, according to him, 
absolutely categorical, and he drew from it the following 
conclusions: — 

**This experiment therefore shows, for the invisible 
rays emitted by salts of uranium, alike th^ double 


refraction, the polarization of the two rays and their 
unequal absorption through the tourmaline." 

We know — for M. Becquerel has since acknowledged 
it — how incorrect these experiments were, and, con- 
sequently, .what a false idea he then entertained of 

** What there is piquant in this," writes Professor de 
Heen on the subject of the polarization and the re- 
flection of the uranium rays, **is, that it took three 
years for M. Becquerel to convince himself that Dr. 
Gustave Le Bon was right, and even then an American 
physicist had to come to the rescue.^ 

M. Becquerel, moreover, gave explanations on this 
matter before the Physical Congress in 1900 in a 
manner that would lead to the belief that he had 
spontaneously discovered his mistake. 

** The experiment on the polarization of the uranium 
rays," he stated, ** did not in the end yield the same 
results either with tourmaline plates or with other 
methods. The same negative conclusions have been 
arrived at by M. Rutherford and M. Gustave Le 

I have indicated the passages in the Comptes rendus 
relating to the first experiments of M. Becquerel ; I will 
now recall those concerning my own. At that period 
(1896-97) I was still confusing two very different 
things: ist, infra-red radiations, which, contrary to the 
teachings of science, passed through, as I proved, most 
non-conducting bodies — wood, stone, black paper, 
ebonite, etc.; 2nd, radiations emitted by metals under 
the influence of light and which I afHrmed to be identical 
with the cathode and uranium rays, as thenceforth 
admitted by all physicists. 

^ Professor Rutherford, who appears to 1^ intended, is, as has 
been said, not an American, but a Canadian. — F. L. 
2 Congres de Physique, t. iii. p. 34. 


Here are a few extracts from my published papers — 

** From the beginning of the year 1897 {Comptes 
rendus^ 5th August 1897, p. 755) I showed that all 
bodies struck by light give birth to radiations of the 
family of the cathode rays." 

A few weeks later I showed the analogy of these 
radiations emitted by bodies under the action of light 
with uranium rays, and concluded my paper with the 
words, ** The properties of uranium must therefore only 
he one particular case of a very general law,'*'' (Comptes 
renduSy 1897, p. 895.) 

My first researches were developed for eight years in 
numerous memoirs, in which I detailed every time new 
experiments. And my first experiments having ap- 
peared to be somewhat forgotten by authors who daily 
rediscovered facts already pointed out by me, I drew 
attention to my anterior publications in a note in the 
Comptes rendus de VAcad&mie des Sciences ^ 1902, p. 32, 
from which I extract the following: — 

**At the very beginning of my researches on the 
mode of energy to which I gave the name of Black 
Light, I stated that the effluves emitted by bodies struck 
by light are of the same nature as the uranium rays, 
which are commonly considered as identical with the 
cathode rays, and as being constituted by the elements 
of dissociated atoms, and the carriers of electric 

** Enlarging the circle of these researches, I demon- 
strated later that similar efflusives were manifested in a 
large number of chemical reactions, and I was able to 
conclude that this production of effluves under very 
varying influences constituted one of the most wide- 
spread of the phenomena of nature. 

** Since that epoch, several authors, Lenard especially, 
have also arrived at this conclusion that metals struck 


by light generate cathode rays which are subject to 
deviation by a magnet. 

** All effluves disengaged under the action of light in 
the conditions just set forth exhibit the closest analogies 
with the emissions now described under the name of 
radio-activity of matter. The production of these last 
therefore does appear to be, as I was a long time alone 
in maintaining, a particular case of a very general law. 
This general law is, that under divers influences, the 
atoms of matter may be subject to a strong dissociation, 
and give birth to effluves with properties very different 
from those of the bodies from which they emanate." 
(Comptes renduSy 1902, p. 32.) 

The loss of memory on the part of certain physicists 
had already struck one of the most eminent of them. 
M. de Heen, Professor of Physics at the University 
of Li^ge, somewhat scandalized by this fact, wrote a 
memoir : Quel est Vauteur de la decouverte des pMno- 
menes dits radio-actifs ? (published by the Institut de 
Physique of Li^ge in 1901) in which, from published 
documents alone, he re-established the truth. 

I had at that time never seen the learned professor, 
and only knew his paper through its being sent to me. 
Had he consulted me before publishing it, I should 
have informed him that the only point I cared for was 
the demonstration of the universality of the radio- 
activity of matter, seeing that the real author of the 
discovery of radio-activity was Niepce de Saint-Victor,- 
who revjealed, fifty years ago, the properties which 
salts of uranium possessed, of emitting for months 
together radiations in the dark, as I will again show 
later on. Those who afterwards brought the question 
entirely up to date were Curie, with his great discovery 
of Radium, and Rutherford with his study of the 
radiation of radio-active bodies. 


The works for popular use due to the disciples of 
M. Becquerel exhibit the above facts in a totally 
different light. In M. Berget's work Le Radium 
may be read, page 37, ** Thereafter the labours of 
M. Becquerel were so many victories : one after the 
other he discovered in 1896 and 1897 that the rays 
emitted by uranium were subject neither to reflection 
by mirrors nor refraction by prisms." This is the exact 
contrary to what M. Becquerel was then persistently 
seeking to demonstrate. The quotations given above 
prove this clearly. 

More than one philosophical lesson can be learned 
from the above. I am not speaking, let it be under- 
stood, of the method of writing history of which the 
above is a specimen ; it has never been written other- 
wise. I simply wish to point out the intensity of the 
illusions which the suggestion derived from preconceived 
ideas may create in the mind of a clever physicist with 
many assistants. If Niepce de Saint-Victor had not 
formerly written that the radiations emitted in the dark 
by salts of uranium were light stored up — that is to 
say, a kind of phosphorescence — M. Becquerel would 
assuredly never have dreamed of considering that they 
must necessarily be refracted, reflected, and polarized. 
Such errors as these easily explain some of the 
enormities written in complete good faith on the sub- 
ject of the N rays. 

In the same book, where I am so harshly dealt with, 
M. Becquerel finally decided, for the first time, to 
mention the name of Niepce de Saint-Victor, having" 
hitherto confined himself to reproducing his experi- 
ments on the salts of uranium and following his pre- 
decessor even in his errors, since he shared his belief in 
a kind of stored-up light. 

Not very equitable towards the living, M. Becquerel 
is still less so towards the dead, and his suppressions 


are at times very unilluminating. Niepce is disposed 
of in a few lines. ** Niepce," he says, ** was unable to 
observe the radiation of uranium because he employed 
plates insufficiently sensitive." 

It is sufficient to read the Comptes rendus of that 
period to see how little foundation there is for this 
assertion. As early as 1867, Niepce observed that salts 
of uraniu^i enclosed in a tin case caused impressions on 
plates in the dark. ** The same activity," he says, ** is 
noticed after several months as on the first day."^ 

If it were true — and such is not at all the case — that 
Niepce de Saint- Victor had actually divined the exist- 
ence of the only body in nature which possessed the 
property of emitting radiations in obscurity, such a 
divination would have been a little more than a stroke 
of genius. 

But Niepce had no such claims. He was a con- 
scientious and patient observer, ignored during his 
lifetime, forgotten when dead. The fact that only two 
physicists have dared to recall to M. Becquerel the 
experiments of Niepce shows how small a degree of 
scientific independence exists in France. 

It is impossible to think without bitterness of the 
opposition offered to Niepce by the official scholars of 
his time. If, instead of endeavouring to ridicule his 
memorable experiments, an attempt had been made to 
repeat them, there certainly would have been found 
some one to think of determining how long the salts of 
uranium could continue, in the darkness, to impress 
plates, exactly as it occurred to M. Becquerel. And if 
Niepce had persisted, as did later M. Becquerel, in the 
mistake of believing in stored-up light, akin to phos- 
phorescence, some one would again have been found to 
show him — as was shown to M. Becquerel — that these 

^ Quoted by M. Guillaume from the Comptes rendus de VAcadimic 
de! Sciences^ 1867, in Radiations Nouvelles, 2nd edition, p. 133. 



radiations, not being polarizable, could not be light. 
Radio-active phenomena would then have been as 
quickly discovered as they were when the demonstra- 
tion of the non-polarization of the uranium rays proved 
that it was a question of something entirely novel. 
In view of the discoveries brought to light by the 
simple fact that uranium preserves* indefinitely its 
powers of impressing a photographic plate .in dark- 
ness, it may be said that the opposition and indifference 
to Niepce de Saint- Victor's experiments have immensely 
retarded the progress of science for more than fifty 

To end definitely a polemic which might continue for 
ever, I do not fear contradiction when I state that to 
judge the work of one who makes researches, the sub- 
ject of them should be examined as to its state before 
and its condition after his researches. 

Now, when I published my experiments in 1897, what 
were the current ideas on the question ? 

istly. It was thought that uranium emitted a kind of 
invisible light. Well, I proved that it emitted some- 
thing entirely new, which was analogous to the radia- 
tions of the family of the X rays, and consequently had 
no relationship whatever to light — a fact which has 
since been completely verified. 

2ndly. It was absolutely unknown that metals struck 
by light acquired properties identical with those of the 
uranium and the cathode rays. I demonstrated this, 
contrary to all accepted ideas. The fact, which has 
long been known, that certain electrified metals lost 
their electric charge under the influence of light, pro- 
ceeded, according to Lenard, from the fact that under 
this influence their surface became pulverized into dust, 
which, disseminated in the air, carried off the electric 
charges of the electrified particles of the metal. 

Lenard, however, was the first to acknowledge his 



error. On the publication of my experiments, he re- 
newed his own, and foynd that metals under the 
influence of light emitted cathode rays which could be 
deviated by a magnet,^ and the experiments were sub- 
sequently confirmed by J. J. Thomson. 

3rdly. At the time referred to it was believed, and M. 
Becquerel believed, that radio-activity was a quite 
exceptional phenomenon belonging to an infinitely 
limited number of bodies. In a series of experiments 
I showed that it was one of the most widespread 
phenomena in nature, produced, not only under the 
influence of light, but under that of heat, and of a large 
number of chemical reactions. This opinion has 
gradually gained ground, and is now almost universally 

In the above enumeration I do not bring into pro- 
minence the demonstration that all these phenomena 
are manifestations of a new force — namely, intra-atomic 
energy, which surpasses all others by its colossal mag- 
nitude. The existence of this force is still in some 
measure contested, and I only desired to recall here 
those facts which are above all dispute. 

4thly. The doctrine of the dissociation of matter was 
only fornlulated a long time after my researches. The 
physicists of the University of Cambridge have become 
its warm partizans, since one of them declared in the 
course of a recent polemic that it was **the most 
important theory of physics"; but they have taken a 
long time to range themselves on its side. In 1900, 
J. J. Thomson, a very eminent scholar, but one who 
easily forgets the work of his predecessors, still believed 
that radio-active emissions were a form of light. This 

^ Lenard's memoir, Erzeugung KathodenstrahUn durch ultra vioUtle 
Licht, was presented to the Academy of Sciences of Vienna on the 
1 8th October 1899. My experiments were published in the Compies 
rendusde VAcadimie des Sciences of Paris, on the 5th April 1897. 


is whut he wrote at that date : ** Becquerel found that 
the radiations of uranium can be reflected, polarized, 
and refracted, so that it is evidently one of the forms of 
light." (Discharge of Electricity through GaseSy p. 57. 

This is what I wrote at the same date at the end of a 
long memoir filled with experiments: **As a general 
conclusion, we may say that under the influence of very 
varied causes — light, chemical reactions, electrification, 
etc. — bodies can dissociate. Matter thus dissociated 
manifests itself under the form of infinitely small 
particles of immense speed, and capable of rendering 
the air a conductor of electricity, and of traversing 
opaque bodies. These particles represent a form of 
matter quite different from those which chemistry has 
made known to us — a new state where the atom is 
probably dissociated. 

**And surely there can be no question here of pro- 
perties only belonging to certain special bodies, such as 
uranium, thorium, etc., for these bodies only represent, 
as I said long since, particular cases of a very general 
law." (Revue Scientifique, p. 458. April 1900.) 

5thly. I will finally add that I was the first to formu- 
late in a special memoir the doctrine that all the 
phenomena of the dissociation of matter are the 
manifestations of a new force — Intra-atomic Energy — 
which surpasses all others by its colossal magnitude, 
and whence are derived, according to my researches, 
the greater part of the forces of nature, especially 
electricity and the heat of the sun. 



Abraham, Max, 33, 45, 190-192 
Aitken, John, 161 
Ampere, 274 
Aristotle, 24, 59 
Arrhenius, 280 


Becquerel, M. Henri, 21-25, 

136, 182, 419-421, 424, 425. 

427, 428 
Benard, M., 98 
Berget, M., 424 
Berthelot, M., 63, 81, 236, 237, 

269, 278, 409 
Blanc, M. A., 176 
Blondlot, M., 149 
Bjerkness, 96, 216 
Bohn, M. Georges, 33 
Bose, Mr., 251 
Bouty, M., 360 
Branly, M., 297, 209, 349. 353, 

360, 366 
Bredig, 297 
Burton, 30/382. 


Campbell, N., 388, 389 

Cartand, M., 259 

Cooke, Dr. Ternent, 140. 

Cornu, 44, 216, 217, 373 

Coste, M., 268 

Crookes, Sir \Vm., 31, 32, 103- 

105, 133, 182, 183 
Curie, M., 25, 42, ^^, 131, 144, 

184, 423 


Darwin, 33 
Dastre, M., 29, 261 
Davy, 184, 231 

De Heen, Prof., 7, 25, 30, 31. 32, 
77,96, III, 170, 355. 358, 421, 

Descartes, 229 

Deslandres» M., 268, 309, 336 

Despaux, M., 71, 72 

Deville, H. Sainte-Claire, 281 

Dewar, Sir James, 253 

Ditte, M., 411, 414 

porn, 115 

Dulx>in, Prof., 284, 385 

Duclaud, M. A., 72 

Dumas, 274 

Dwelshauvers-Dery, Prof., 2 


Eder, 341 

Elsler, *Prof., 31, 149, 157, 360, 

400, 417 
Ernecke, 417 


Faraday, 13, 109, 220, 221, 231, 

232, 271. 274 
Fleming, Prof., 206 
Fresnel, 87, 91, 274 


Galileo, 59, 274 
Galvani, 50 

Garrigou, Prof., 299, 402 
Gates, Miss, 155 




Gautier, M. Armand, 70, 97, 

283, 284, 301 
Geitel, Prof., 31, 149, 157, 360, 

400, 417 
Giesel, Prof., 25, 156 
Guillaume, M., 425 


Helmholtz, 58, 68, 220 

Henry, Prof. Chas., 285 

Hertz, 360 

Hewitt, Cooper, 226 

Heydweiler, Dr., 182 

Him, 89 

HoflF, Van't, 246 

Huff, Prof., 150 


Janet, M. Paul, 52 
Jevons, 26 


Kalahne, Dr., 154, 155 
Kaufmann, Prof., 190, 191 
Kelvin, Lord, 55, 56,68,89,91,229 
Kleeman, Mr., 396 
Kolbe, Prof., 329 


Laisant, M., 73, 74 

Lamarck, 3, 33 

I^ngevin, M. P., 33 

Laplace, 153, 241, 310 

Larmor, 83, 92, 96, 114, 191, 234 

Lavoisier, 5, 14, 81, 153, 161, 280 

Le Bon, Guslave, 23, 29, 30, 32, 

33*69, 7i-73» 75-79, i", ^S, 

284, 355» 387, 4i9» 421 
Leduc, M. Stephane, 168, 209, 

211, 243, 246 
Leggc, F., 417 
Lehmann, 256 
Lenard, Prof., 31, 85, 112, 127, 

345. 371. 372. 422, 426, 427 
Liebig, 51 
Lippmann, M., 223 
Lorentz, Prof., 114 
Lucretius, 5, 228 


MacClelland, Prof., 140 
McKendrick, Prof., 237 
McLennan, 30, 382 
Mariotte, the law of, 104, 286 
Martin, Ml, 387, 388 
Marx, Prof., 128 
Mascart, M., 56, 373 
Massart, 246 
Maxwell, 91, 196 
Mayer, Robert, 58 
Mendeltfeff, Prof.. 89 
Meyer, 25 
Michaux, M. F., 2 
Moissan, M., 280 
Muller, M., 88 


Naguet, Prof., 15, 69 
Nernst, Dr., 233 
Newton, Isaac, 69, 229 
Niepce, 21, 22, 26, 423, 426 
Nodon, 31 


Ohm's law, 57, 58, 216 
Ostwald, 261, 281, 282 
Gudin, Dr., 206, 211, 212 


Painleve, M. Paul, 69 
Parodi, Dr., 278 
Pender, M., 223 
Pio, Prof., 76 
Poincar^, Henri, 68, 69 
Poincar^, Prof, Lucien, 29, 274 
Poulsen, 250 


Quincke, Prof., 99, 257 


Ramsay, Sir Wm., 140, 280, 329 

376, 400 
R^, Prof. Filippo, 66, 74 
Rembrandt, 264 



Robin, M., 299 

Roche, M., 169 

Roentgen, Prof., 232, 356 

Rowland, 223 

Rutherford, Prof., 23, 31, 45, 56, 
108, III, 115-117, 123, 131, 
132, 134, 138, 141, 142, 144, 
148, 155» 156, 181-183, 238, 
322, 324, 359, 398, 421, 423 


Sagaret, M., 78 
Sagnac, M., 126, 127 
Schron, Prof., 258, 259 
Schuman, 373 
Schumann, 127 
Schweidler, 25 
S^n^chal, £., 2 
Soddy, Prof., 115, 127, 181 
Somerhausen, Prof., 75 
Spencer, Dr., 329, 376 
Spencer, Herbert, 15 
Spring, 256 
Steele, H., 250 
Stokes, Sir G., 212 
Strutt, Hon. R. J., 30, 134 
Sutherland, 96 


Thomson, Prof. J. J., 7, 44-46, 
66, 90, 114, 115, "7, 120, 123, 

125, 136, 138, 148, 152, 158, 
159, i95» 206, 209, 221, 238, 

322, 345. 350. 379, 388, 394, 

Turpain, M., 176 
Tyndall, 175 


Valenta, 341 
Verneuil, M,, 266 
Villard, M., 145, 350 
Volta, 16, III, 274 
Vries, 246 


Waals, Van dcr, 256 

Watteville, 308 

Wesendonk, Dr. von, 418 

Weyher, 96, 97 

Whetham, Mr., 27 

Wigger, 322^ 

Wilson, C. t. R., 123, 161, 382 

Wilson, Prof. H. A., 195 

Wismann, 238 

Wyrouboff, M., 266 

Zbeman, Prof., 225 



Absorbents, 334 

Academy of Sciences, 27, 278 

Academy^ The, quoted, 31 

Acetylene, formation of, 154, 290 

Actinium, 139 

Actions, catalytic, 303 

Affinity, 239, 240, 241 

Aigrettes, 203, 204, 206 

Air, the, a conductor of electricity, 

I55> 2^* 323 * ionization of, 

Alexins, 293 

** Allotropic*' stales, 267, 268 
Alloys, 278 
Aluminium, 135, 277, 405, 40F, 

Amber, 324 

Annie Scientifiqtte, quoted, 78 
Anti-toxins, 293 
Archives des Sciences Physiqtus de 

Genkve, quoted, 56 
Astronomy, 308 
Atoms, I, 105, 116, 235, 247, 349; 

structure of, lo, 228; electric, 

114, 128, 144, 14s, 224. 312, 

313; genesis and evolution of, 

Attractions, 163, 240, 241247 

Aurora borealis, 158 


Bacteria, 237, 261, 301 

Balance, the, 95 

Benzene, 290 

Bismuth, 145 

Bodies, simple, unity of the com- 
position of, 263-273 ; are they 
elements of an unvarying fixity, 
265 ; variability of, 274 

Bodies, compound, variability of, 

— isomeric, metameric, polymeric, 

— radio-active, 323, 325^ cause of 
the dissociation of, 390 

— transparency of, determined by 
photography, 335 

— dissociation of, by light, 345, 

Bolometerj the, 249, 250 


Cacodyl, 289 

Cadmium, 140 

Caffeine, 285 

Calcium, sulphide of, 145. 180 

"Canal rays," 122 

Cells, artificial, 244, 245 

Chemistry, kinematic, 292; intra- 
atomic, 296, 306 

Chlorophyll, 283 

Cohesion, 239, 240, 241 

Combustion, dissociation of matter 

^y» '57> 377 J ioiis produced by, 

Comptes rendus de VAcadcmte des 

Sciences , 19, 21, 22; quoted, 

Copper, 332 
Corposants, 168 
Corpuscles, 114, 120, 136, 236, 

Crystals, semi-liquid, 256-262 

Current, electric, 204; voltaic, 

220, 222 


Diastases, 283, 293, 300 
Dissociation o( bodies, 345, 346 





Edifices, molecular, forces which 
maintain, 238-241 ; chemical, 

Effluves, 6, 24, 63, 85, loi, 105, 
112, 151, 196, 207, 208, 275, 

330». 338, 341, 346, 349. 416 
Electric machine, elements emitted 

by the poles of an, 205 
Electricity, origin of, 61-64, 162; 

ionic, 109; considered as a 

semi-material substance, 198; 

modern theory of, 220; static, 

222; air a conductor of, 323; 

apparatus for reducing the loss 

of, 325 ; leak of, 369 
Electrodes. 226, 341, 368 
Electrolysis, 264, 270 
Electrometer, the, 125 
Electrons, 96, 98, iii, 114, 115, 

120, 128, 135, 204, 220, 227, 

233, 234, 322 
Electroscope, 324, 325, 327 
Elements, material, chemical 

equilibria of, 288 
Emanations, 115, 132, 159, 326 
Energy, intra-atomic, 5-18, no, 

202, 239, 295, 305, 427, 428 

history of discovery of, 19-34 

forces derived therefrom, 

35. 60-67 

, existence of, 35-39 

its magnitude, 35-51 

power of, 36 

quantity contained in matter, 

*- forms under which it can be 

condensed in matter, 46-49 
the utilization of, 49-51 

— — objections to the doctrine 
of, 68-79 

— kinetic, 209, 234, 235 
English Mechanic^ quoted, 31, 76 
Enzymes, 300 

Equilibria, chemical, of mineral 
substances, 288 ; of organic 
substances, 291 ; oscillating, 304 

Equilibrium, different forms of, 
94-100, 241 

Ether, 11, 13, 82» 87*93, 94-100, 

Etherification, 294 
Extrapolation, 193 


FiBLD, electric, 222, 224; mag- 
netic, 121, 124, 126, 131, 136, 
169, 209, 224, 322, 423 

Fire, St. Elmo's, 168 

Fluid, ionic, 119 

Fluids, electric and material, com- 
parison of, 2x6 

Fluorescence, 150, 212, 322 

** Foam cells," 99 

** Foam structure," 257 

Force, the element of, i, 9, 14; 
centrifugal, 234; lines of, 221, 
223, 246 • 

Forces, molecular, origin of, 60-61 

Formene, 291 

Formiate, 302 


Galvanometer, the, 95, 324 

Gas, marsh, 291 

Gases, dissociation of the atom's 
of» 370 » action of, 377 ; ioniza- 
tion of, 394 

Glucose, 301 

Gravitation, 218, 219 

Gyroscope, the, 169 


HAEMOGLOBIN, 283, 284 

Heat, solar, origin of, 64-67, 162 ; 

dissociation of matter by, 158; 

radiant, 312 
Heliostat, 330 
Helium, 115, 140, 253 
Hydration, 390 
Hydrodynamics, 256 
Hydrogen, 253 
Hydrostatics, 256 


Imponderable, the world of the, 

Inertia, 194-196, 253 
Iodoform, 237, 403 




Ions, positive and negative, 115, 
116, 132, 210, 233, 323; pro- 
duced by combustion, by chemical 
reaction, and by the oxidation 
of phosphorus, 397 

Iron, pyrophoric, 279 

Isomerism, 290 


Lamps, incandescent, 282 
Light, the action of, 6, 94, 345, 
358, 369; Black, 32, 422; dis- 
sociation of matter by, 151; 
solar, 152, 330, 342; visible, 
312; invisible, 313; leak caused 
by, 360 
Liquids, 257 ^ 

Lumiire emmasasitue^ 22 
Lumiire noire, 20, 21, 29, 31 
Luminescence, invisible, 21 
Lyrsea, 309 


Magnesium, 277, 404, 407 
Magnetism, 220 
"Magnetons," 145 
Mass, indestructibility of, 17; 

variations of, 191 
Matter, the element of, 1,3, 17 

— not eternal, i 

— new ideas on, 5 

— indestructibility of, 5, 15, 149 

— dissociation of, 7, 35, 374, 415; 
history of the discovery of the, 
19-34, 419; interpretations of 
the experiments which reveal 
the, 101-112; characteristics of 
the elements furnished by the, 
115-129; by light, 151, 331 ; by 
chemical reaction, 153, 383; by 
electric action, 156; by com- 
bustion, 157; by heat, 158; 
spontaneous, 159, 399; artificial 
equilibria of the elements arising 
from the, 163; mechanism of 
the, 177; methods of observa- 
tion for verifying the, 322; ex- 
periments on the, 338; during 
the formation of gases, 385-386; 
during the oxidation of phos- 
phorus, 386 

Matter, propositions on, 8-9 

— and force, 9, 14 

— and ether, 13, 81-86, loi; the 
intermediate world between, 

— and energy, 13, 82 

— vanishing of, 14, 16, 307 

— quantity of energy contained in, 


— forms under which energy can 
be condensed in, 46-49 

— transformed into energy, 52- 


— dematerialization of, loi, 131, 

322; products of the, 11 3-1 15; 
causes of the, 148-15 1 

— how it can dissociate, 172-187 

— birth, evolution, and end of, 
228-247, 307-319 

— constitution of, 228, 230 

— magnitude of the elements of 
which it is composed, 236 

— possesses an intense life, 247 

— mobility and sensibility of, 

— equilibria of, 252 ; unknown, 

— various aspects of, 256 

— transparency of, 349 

— division of, 403 

Mercury, 277, 339, 357, 404, 405, 

Metals, cells in, 259 ; colloidal, 

269, 297 
Meteorology, 345 
Methane, 291 
Micro-organisms, 259, 301 
Microbes, 236, 259 
Molecules, 117, 238, 240, 241, 

Musk, 237, 403 

Mycoderma acetic 299 


Nature, 6, 13, 76, 171, 229, 

Nature, 27, 196 

Navy, the, 414 

Nebulae, 308 

Nicotine, 283 

Nirvana, 315 




** Organic molecules," 238 
Oxygen, formation of, 154, 254, 

Ozone, 290 


Particles, electric, 115, 116. 

122, 202, 203, 220, 234 
Phenomena, natural, part taken 

by the dissociation of matter in, 

Philosophical A/agazitte, quoted, 

55, 181 
Phosphorescence, 145, 155, 186, 

276, 322, 384, 388 
Phosphorus, oxidation of, ions 

produced by, 397 
Photography, use of, 335, 343, 

Polonium, 21, 136, 150, 156, 322 

Polyhedra, 246 

Polymerization, 294 

Ponderability, the world of, 228 

Ponderable and imponderable, the 

separation between, 80 

Pressure, osmotic, 243, 245, 246 


Quinine, hydration of sulphate 
of, 154 


** Radiant matter," 31 
Radio-activity, 7, 25, 30, 31, 37, 

133. I43» 146, I55> 181, 276, 

323. 357. 388, 403, 419 
Radio-tellurium, 150 
Radium, 2, 6, 21, 26, 42, 57, 76, 

77, III, 115, 117, 122, 130. 

136, 139. 183, 322, 357, 390, 

«* Hard earths," 266 
Rays, cathode, 5, 20, 24, 26, 30, 

76, 86, 101-105, 115, 121, 224 
— Rontgen, 31, 149 
--X, 5, 25, 30-32, 38, 57, loi, 

102, 105, 106, 109-11, 115, 116, 
120, 122, 126, 127, 137, 199, 
200, 208, 209, 224, 232, 373, 
418, 426 
Reaction, chemical, dissociation of 
matter by, 153, 232; ions pro- 
duced by, 397 
Repulsions, 163, 240, 241-247 
Researches, experimental, 321 el 

Remte des Deux Mondes^ quoted, 

Revue des Id^es^ quoted, 33 
Revue d'llalie^ quoted, 69 
Revue Cenerale des Sciences^ 

quoted, 30 
Revue Philosophique, quoted, 79 
Revue Scientifiquey 30; quoted, 
69, 71, 72, 98. 284 


Saliva, 283 

•* Saturation current," 119 

Science, a revolution in, 75 

Selenium, a conductor of elec- 
tricity, 268 

Sirius, 309 

Sodium, 85 

Species,. chemical, variability of, 
274, 404 

Spectrograph, 333, 338 

Spectroscope, 308 

Spectrum, the, 152, 158, 211, 338, 

343. 374 
Speed, variations of, 191 

Spermatozoon, 238, 262 

Spinthariscope, the, 133, 209 

Spores, 237 

Stereo-chemistry, 292 

Strontium, sulphide of, 180 

Structures, atomic and molecular, 

causes capable of modifying, 

Sub-atoms, 68 
Substances, mineral, chemical 

equilibria of, 288 
— radio-active, 130, 131, 138, 

390. 399; causes capable of 

producing the dissociation of, 




Sulphide, phosphorescent, 134 
Sun, the, 158, 363 


Telegraphv, wireless, 224 
Tension, osmotic, 243 
Theobromine, 285 
Thermo-chemistry, 269, 270, 271 
Thermo-dynamics, 8, 52, 56, 69 
Thermometer, the, 95 
Thorium, III, 115, 122, 130, 139, 

357» 390 
Tin, 339 

Toxins, 293, 300. 301 
Transparency, table of, 336 


Units, electro- magnetic, 125 
Universe, immaterial basis of the, 

Uranium, 5, 6, 20-22, 26, 105, 

III, 130, 357, 390 


Vacuum, 117, 123 
Vanilla, 403 


Watrr, decomposition of, 154, 

406, 407, 410 
Water- vapour, 125, 303 
Wave- lengths, 336, 339. 340, 349. 

Waves, calorific, 213 ; Hertzian. 

121, 176, 211, 213, 214, 250, 

312, 333. 349, 35i» 353 
Wind, electric, 209 

World of the imponderable, the, 



Yeast, .301 

Zymase, 301 




Page 9, line 15, for "instable" r^<z^/ unstable. 

13 »> 30f for "Nature and Energy" r^«fl? Matter and Energy. 

17 »» 5 and 6, for ''measured by its weight, remained " r^a</ 
measured by its weight — remained. 

18 ,,20, for "something very simple, governed " r^o^/ something 
very simple and governed. 

29 )) 31, for ** In one of the annual reviews " read In one of the 

37 »j 9» for "phenomena" r^a^/ phenomenon. 

37 , , 22, for " to " read. of. 

38 , , 9, for "of succeeding in dissociating " read of dissociating. 
38 ,, 10, for "we could dissociate " r^«fl? we could manage to 

38 ,, 20, for " phenomena " r^dwf — phenomena. 
38 ,, 25, for " define " r^ad^ verify. ^ 

42 , , 23, for " an " read per. 

45 j> IS» for **liave reached" readhscvt sometimes reached. 
45 ,, 16, for "sometimes very much higher" readvtxy much 

48 ,, 6, for "kilogrammes" r^awf kilometres. 
54 ,, 31 and 32, "condensation, in immense quantities, 

within " read condensation in immense quantities within. 
57 >» 3^1 "the history of sciences" read the history of the 

62 ,, 2, for "must always bear in mind to understand " r^oaT 

must always bear in mind in prder to understand. 
70 ,, 2 and 5, for " instable " r^aaf unstable. 
81 ,,9, for " Physics, in fact, still maintains a wide separation" 

read Physics in fact still maintains that a wide separation. 
,, 82 ,, 12, for " matter and energy, reproduced " read matter and 

energy reproduced. 
j» 87 ,, 19, for " prominent parts " r^fl^ crest. 
87 ,, 20, for "hollow parts" r^aaf trough. 
90 ,,20, for " that is to say, their mass, is " read that is to say 

their mass — is. 
93 »» 5i for "and thus" read dsiA thus to. 














» I 

438 ERRATA. 

Page 94, line 20, for "instable" r^fl^ unstable. 
M 95 »» 8, for ** vibrations and vortices" read vibrations, and 

5» 95 >» '5» ^or "the thermometer, the attractions" read\}a& ther- 
mometer the attractions. 
99 ,, 10, for ** fixed and cast in layers" read fused and cast in 

thin layers. 
116 ,, 27, for "aggregate of electrons and neutral particles 
form " read aggregate of electrons and neutral particles 
123 ,, 24-26, for " bodies are found, has proved, as has just been 
said, the cathode rays and the emission from radio-active 
their identity" read the cathode rays and the emission 
from radio-active bodies are formed, has proved, as has 
just been said, their identity. 
,, 127 ,, 24, for "For the extreme violet " r^a^ For the extreme 

25, for ".160/A to .loo/ti" reado,i6oti to o.icx)/i. 
3, for * ' phenomena " read phenomenon. 
9, for "recover" r^a^find. 
18, for "temperatures," r^a^ temperatures. 
22, for " leads " read lead. 
13, for " radiations " read the radiations. 
17, for "at times powerfully modify" read powerfully 

26, for "became" r^a^ becomes. 
31, for "instable" r^adT unstable. 

17, for "from its condition as an electrified body" read 
from their condition as electrified bodies. 
24, for " magnetic " read negative. 

18, for "under \ = .230/1*" «a</ under \ = 0.230/*. 
II, for " . 230/1* " read o. 230/*. 

18 and 19, for "they hardly propel themselves farther" 
read they are hardly propagated farther. 

,, 234 ,, 24, for " state of rapid motion" read state of rapid motion 
within the atom. 
251 II 9, for " delicate sign in life " read delicate sign of life. 
264 ,, 4, for "quantity of heat, expressed in calories" read 

quantity of heat expressed in calories. 
266 ,, 3, for " to acquire, a knowledge " read to acquire a know- 
n 269 ,, 5, for "Recent researches in colloidal metals, which we" 
read The recent researches in colloidal metals which we. 






























» > 


ERRATA. 439 

Page 295, line 17, for ** would paralyze all efforts" read would then 
paralyze all our efforts. 
,, 306 ,, 21, for ** we barely see" readyre see. 

311 ,, 21, for ** assume to affect " read assume to effect. 

312 ,, II, for "continued to exist, since their formation" read 
continued since their formation. 

315 ,, 24, for * * nor " rdfl^ or. 

318 ,, 22, for ** truths approximately true" r^dw? truths which are 

approximately true. 
321 ,, 15, for ** very simple experiments, and consequently easy" 

read only experiments very simple and consequently easy. 

1 of Figure description, for *' reducing" r^aa^ evidencing. 
4 ,, ,, for "capsule placed on the" r^a/ 

capsule on the. 

23, for * * derivation " read deviation. 
4, for ** dissociated matter by light" read msiiier dissoci- 
ated by light. 

10, for " propelled" r^o^ propagated. 

2 of Note, for " positively " r^a^/ negatively. 

24, for "radiations of the end of the spectrum" read 
radiations at the end of the spectrum. 

I of Note, for "charges'* read chsinges, 
7, for " corbide " read carbide. 

27, for "an" read the, 

28, for " only 0.2 thick" read only 0.2 mm. thick. 

11, for "closely" read slovfly, 
4 and 5 of Note 2, for " spark gap sheltered from the light 

of I cm." read spark gap of I cm. sheltered from the 






> J 
























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XXXVI. DEGENERACY : Its Causes, Signs, and Results. 
By Professor EUGENE S. Talbot, M.D., Chicago. With 

*' The author is bold, original, and suggestive, and his work is a con- 
tribution of real and indeed great value, more so on the whole than anything 
that has yet appeared in this country." — American Journal of Psychology, 

XXXVII. THE RACES OF MAN: A Sketch of Ethno- 
graphy AND Anthropology. By J. Deniker. With 178 

'* Dr. Deniker has achieved a success which is well-nigh phenomenaL'' — 
British Medical Journal, 

Empirical Study of the Growth of Religious Con- 
sciousness. By Edwin Diller Starbuck Ph.D., Assistant 
Professor of Education, Leland Stanford Junior University. 

**No one interested in the study of religious life and experience can 
afford to neglect this volume." — Morning Herald, 

New York : Charles Scribnb&'s Sons. 

XXXIX. THE CHILD : A Study in the Evolution of Man. 
By Dr. Alexander Francis Chamberlain, M.A., Ph.D., 
Lecturer on Anthropology in Clark University, Worcester 
(Mass.). With Illustrations. 

*' The work contains much cuiious information, and should be studied by 
those who have to do with chWdiXQn" —Sheffield Daily Telegraph, 


With over loo Illustrations. 

'* M. Sergi has given us a lucid and complete exposition of his views on a 
subject of supreme interest." — Irish Times, 

Jun., Ph.D., Professor in the University of Pennsylvania. 

**This work presents a careful survey of the subject, and forms an 
admirable introduction to any particular branch of it." — Methoiist Times. 

By Karl von Zittel. 

"It is a very masterly treatise, written with a wide grasp of recent 
discoveries. " — Publishers^ Circular, 

parative Education. By R. E. Hughes, M.A. (Oxon.), 
B.Sc. (Lond.). 

" Mr. Hughes gives a lucid account of the exact position of Education in 
England, Germany, France, and the United States. The statistics 
present a clear and attractive picture of the manner in which one of the 
greatest questions now at issue is being solved both at home and abroad." 
— Standard, 

XLIV. MORALS: A Treatise on the Psycho-Sociological 
Bases of Ethics. By Professor G. L Duprat. Trans- 
lated by W. J. Greenstreet, M.A., F.R.A.S. 

** The present work is representative of the modern departure in the 
treatment of the theory of morals. The author brings a wide knowledge 
to bear on his subject." — Education, 

Charles Davison, D.Sc, F.G.S. With Illustrations. 
** Dr. Davison has done his work well." — Westminster Gazette. 

[Several New Volumes in the Press.] 

New York : Charles Scribner's Sons.